Method and apparatus for placing a catheter within a vasculature

ABSTRACT

A catheter for insertion into vasculature of a patient to a target area in the vasculature includes a hollow inner shaft, a non-occluding self-expandable scaffold coupled to the distal end of the inner shaft and disposed at the distal end of the inner shaft, and a hollow outer shaft. The outer shaft is slidable over the inner shaft and scaffold such that the scaffold is in a non-expanded state when the outer shaft is around the scaffold. The outer shaft has a state where the distal end of the outer shaft remains near the target area without the inner shaft and the scaffold being within the outer shaft. The inner shaft and the scaffold are removable through the proximal end of the outer shaft while the distal end of the outer shaft remains near the target area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/223,458, filed Mar. 24, 2014, which issued asU.S. Pat. No. 9,125,683 on Sep. 8, 2015, which is a continuation-in-partof: (1) U.S. patent application Ser. No. 14/060,381 filed Oct. 22, 2013;(2) U.S. application Ser. No. 13/842,744, filed Mar. 15, 2013; and (3)U.S. application Ser. No. 13/166,623, filed Jun. 22, 2011, the contentsof each of which are incorporated by reference in their entireties.

U.S. patent application Ser. No. 14/060,381, which issued as U.S. Pat.No. 9,358,037 on Jun. 7, 2017, is a continuation-in-part of U.S.application Ser. No. 13/842,744, and claims priority to U.S. ProvisionalApplication No. 61/793,268, filed Mar. 15, 2013, and U.S. ProvisionalApplication No. 61/716,856, filed Oct. 22, 2012, the contents of each ofwhich are incorporated by reference in their entireties.

U.S. application Ser. No. 13/842,744, which issued as U.S. Pat. No.9,126,020 on Sep. 8, 2015, is a continuation-in-part application of U.S.application Ser. No. 13/166,623, and claims priority to U.S. ProvisionalApplication No. 61/716,856 the contents of each of which areincorporated by reference in their entireties.

U.S. application Ser. No. 13/166,623, which issued as U.S. Pat. No.8,764,730 on Jul. 1, 2014, is a divisional application of U.S.application Ser. No. 12/147,130, filed Jun. 26, 2008, which issued asU.S. Pat. No. 7,988,646 on Aug. 2, 2011, which claims priority to U.S.Provisional Application No. 60/929,395, filed Jun. 26, 2007, U.S.Provisional Application No. 60/960,900, filed Oct. 19, 2007, U.S.Provisional Application No. 60/996,057, filed Oct. 26, 2007, and U.S.Provisional Application No. 61/064,715, filed Mar. 21, 2008, thecontents of each of which are incorporated by reference in theirentireties.

FIELD OF THE INVENTION

The invention relates generally to an apparatus and methods for treatingvasculatures, and, more particularly, to methods and apparatus forcrossing a chronic total occlusion of a vasculature and/or providingsupport and centering to facilitate a guidewire to cross through achronic total occlusion.

BACKGROUND

A chronic total occlusion in a coronary artery, peripheral artery, vein,dialysis fistula, or other types of vasculature represents a challengefor percutaneous treatment. Percutaneous treatments are generallypreferred revascularization options as compared to bypass surgery.Continuing improvements in equipment specifically developed for chronictotal occlusions have allowed success rates to improve. Although thesuccess rates for these types of procedures have improved, theprocedures for percutaneous treatments still suffer from severaldrawbacks.

Patients without a successful percutaneous treatment may need to undergobypass surgery or experience continuing symptoms from the occlusions.

A major obstacle within a chronic total occlusion may often beencountered while attempting to advance a catheter across the chronictotal occlusion in a vasculature. A maximum resistance may be met at themost proximal point of the lesion, i.e. the firm, fibrous cap. Whilebeing advanced, a catheter may tend to deflect away from the fibrous captowards the adventitial layer, often entering a false lumen. Thisoff-axis displacement of the catheter often may result in a proceduralfailure.

Successful passage of the catheter may also be obstructed by randomlylocated calcified regions of atherosclerotic plaque within the mass ofthe lesion. Microchannels within the obstruction may be desirabletargets for the tip of the catheter. However, these soft spots withinthe lesion are difficult to identify angiographically and are dispersedrandomly within the matrix of the lesion.

Coronary arteries and other vasculatures tend to be non-linear conduits,often coursing over the surface of the epicardium and other tissues. Thesuccess of current technology is limited by this type of geometry. Incurrent systems, a catheter or currently available catheter is advanceddown a vasculature to the level of the obstruction. The catheteradvancement may tend to proceed along the outer, greater curvature ofthe vasculature.

As a result, only a minor portion of the surface area of the obstructionmay be encountered with sufficient force to allow passage of thecatheter. On many occasions, the angle of encounter and/or the forceapplied to the fibrous cap may not be sufficient for crossing thefibrous cap with the catheter. If the tip of the catheter is curvedprior to placement through the support catheter, direct longitudinalforce may be compromised as the wire is advanced off axis. If a rapidexchange catheter system is used as catheter support, the catheter maybuckle within the guide-catheter resulting in suboptimal longitudinalcatheter force.

At times, a single lumen angioplasty balloon may be inflated justproximal to the chronic total occlusion in an attempt to center thecatheter in the vessel lumen and provide additional support for thecatheter. The angioplasty balloon, however, is occlusive to nearbyvessels and exerts a significant outward force on the native vessel.

Approximately one-third of patients with coronary artery disease (CAD)and half of patients with peripheral artery disease (PAD), present witha chronic total occlusion (CTO) in the vessel. Despite overwhelmingevidence of improved outcomes, attempted interventions remain low due tothe lack of effective and convenient interventional tools. CTOs arecharacterized by fibrous caps with small micro-channels often intortuous anatomy, leading to challenges for clinicians to gain guidewireaccess to treat the underlying disease.

In some situations, following an initial advancement of a first catheterto or through the cap of the occlusion, additional instruments orcatheters may be subsequently advanced proximal to or through theocclusion. This may require removal of the first catheter and placementof a second catheter proximal to the occlusion. In placing the secondcatheter, the anatomy of the patient must be again be navigated,including the tortuous inner lumens of the heart, for example. However,the usual risks of the catheter being diverted off-course remain.Additionally, even if a guide wire is used, passage of the catheterthrough this anatomy can be traumatic for vessel walls.

Generally, needs exist for improved apparatus and methods for treatingvasculatures.

More specifically, needs exist for improved apparatus and methods forefficiently and effectively passing a guidewire through a chronic totalocclusion in a vasculature. In particular, there exists a need forimproved apparatus and methods for efficiently and effectively passing aguidewire through a chronic total occlusion in a vasculature in such away that the guidewire is reliably centered in the chronic totalocclusion. Furthermore, there exists a need for improved apparatus andmethods for navigating the vasculature in a way that is simple,reliable, and less traumatic to the vasculature.

SUMMARY OF THE INVENTION

One embodiment of the invention is a catheter apparatus for insertioninto vasculature of a patient and to a target area in the vasculature.The catheter apparatus may include a hollow inner shaft with a distalend and a proximal end; a non-occluding self-expandable scaffold coupledto the distal end of the inner shaft and disposed at the distal end ofthe inner shaft, a portion of the distal end of the inner shaft beingdisposed at least in part inside the self-expandable scaffold; and ahollow outer shaft with a distal end and a proximal end. The outer shaftmay be slidable over the inner shaft and the scaffold such that thescaffold is in a non-expanded state when the outer shaft is disposedaround the scaffold. The outer shaft can have a state where the distalend of the outer shaft remains near the target area without the innershaft and the scaffold being within the outer shaft. The inner shaft andthe scaffold can be removable through the proximal end of the outershaft while the proximal end of the outer shaft remains near the targetarea.

One embodiment of the invention is a method of using a catheter in avessel of a patient for crossing a target area and providing support fora medical device. The catheter includes a hollow shaft with a distal endand a proximal end, and a non-occluding self-expandable scaffolddisposed at the distal end of the catheter. A portion of the distal endof the catheter is disposed at least in part inside the scaffold. Thecatheter also includes a sheath with a central lumen, a distal endhaving a distal opening, and a proximal end having a proximal opening.The sheath is slidable along the shaft, and the scaffold may be coupledto the distal end of the catheter. The scaffold can be in an un-expandedstate when covered by the sheath. The method may include withdrawing thesheath to expand the self-expandable scaffold. The method may alsoinclude inserting a catheter into a vessel; moving the sheath and thescaffold structure relative to each other to position the sheath atleast partially over the scaffold structure so that the scaffold returnsto the un-expanded state; and withdrawing the hollow shaft and thescaffold out through the proximal opening of the sheath. The sheath mayremain in the vessel as a support catheter such that a medical devicemay be passed through the proximal opening of the sheath and advancedthrough the sheath to a target area near the distal end of the sheath.

Additional features, advantages, and embodiments of the invention areset forth or apparent from consideration of the following detaileddescription, drawings, and claims. Moreover, it is to be understood thatboth the foregoing summary of the invention and the following detaileddescription are exemplary and intended to provide further explanationwithout limiting the scope of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe invention, will be better understood when read in conjunction withthe appended drawings. The accompanying drawings, which are included toprovide a further understanding of the invention and are incorporated inand constitute a part of this specification, illustrate preferredembodiments of the invention and together with the detailed descriptionserve to explain the principles of the invention. In the drawings:

FIG. 1A is a view of the proximal end of a catheter apparatus inaccordance with principles of the invention.

FIG. 1B is another view of the proximal end of a catheter apparatus inaccordance with principles of the invention.

FIG. 2A is a partial cross-sectional view of a distal end of a catheterapparatus in accordance with principles of the invention.

FIG. 2B is a view of a distal end of a catheter apparatus in accordancewith principles of the invention.

FIG. 2C is a cross-sectional view of the self-expandable scaffoldstructure at the distal end of a catheter apparatus in accordance withprinciples of the invention.

FIG. 3 is a view of a distal end of a catheter apparatus in accordancewith principles of the invention.

FIG. 4 is a view of a distal end of microcatheter in accordance withprinciples of the invention.

FIG. 5 is an unwrapped view of one embodiment of a scaffold of acatheter apparatus in an expanded state in accordance with principles ofthe invention.

FIG. 6 is an unwrapped view of an embodiment of a scaffold includingloop members in a partially expanded state in accordance with principlesof the invention.

FIG. 7 is perspective view of another self-expanding scaffold in anexpanded state positioned on a shaft of a catheter apparatus inaccordance with principles of the invention.

FIG. 8A shows a perspective view of an embodiment of a scaffold attachedto a shaft in accordance with the principles of the invention.

FIG. 8B shows a perspective view of an embodiment of a loop member of ascaffold in accordance with the principles of the invention.

FIG. 9A is a view of a distal end of a catheter apparatus according toone embodiment of the invention.

FIG. 9B illustrates an embodiment of the steps during a method of usingthe catheter apparatus shown in FIG. 9A.

FIG. 9C is a close-up view of a distal end of a catheter apparatus shownin FIG. 9A according to an embodiment of the invention.

FIG. 9D is a distal end view of the catheter apparatus shown in FIG. 9Caccording to an embodiment of the invention.

FIG. 10A is a side view of an alternate embodiment of a scaffoldaccording to the principles of the invention.

FIG. 10B is perspective view of the scaffold of FIG. 10A in accordancewith principles of the invention.

FIG. 10C is an unwrapped view of the alternate embodiment of a scaffoldof the type shown in FIGS. 10A and 10B, but having an alternateconfiguration in accordance with principles of the invention.

FIG. 11A is a view of a distal end of a catheter apparatus showinganother embodiment of a scaffold in accordance with principles of theinvention.

FIG. 11B is a view of a distal end of a catheter apparatus showing yetanother embodiment of a scaffold in accordance with principles of theinvention.

FIG. 11C is a view of a distal end of a catheter apparatus showing of analternate embodiment of a scaffold in accordance with principles of theinvention.

FIG. 12A shows a proximal end of a catheter apparatus when a scaffold isdisposed within a sheath according to one embodiment of the invention.

FIG. 12B shows a distal end of a catheter apparatus of FIG. 12A with thescaffold within the sheath according to one embodiment of the invention.

FIG. 12C shows a proximal end of a catheter apparatus of FIG. 12A whenthe scaffold is uncovered by the sheath according to one embodiment ofthe invention.

FIG. 12D shows a distal end of a catheter apparatus of FIG. 12A with thescaffold uncovered by the sheath according to one embodiment of theinvention.

FIG. 13A illustrates an embodiment of steps during a method of using thecatheter apparatus shown in FIG. 12A according to one embodiment of theinvention.

FIG. 13B illustrates an embodiment of additional steps during a methodof using the catheter apparatus shown in FIG. 12A according to oneembodiment of the invention.

FIG. 14 shows a proximal end of a catheter apparatus according to oneembodiment of the invention.

FIG. 15A-15E illustrates an embodiment of the steps during a method ofusing the catheter apparatus shown in FIG. 12A.

DETAILED DESCRIPTION

Embodiments of the present invention solve many of the problems and/orovercome many of the drawbacks and disadvantages of the prior art byproviding an apparatus and method for treating vasculatures.

Embodiments of the present invention may include an apparatus andmethods for advancing one or more catheters, preferably, microcathetersthrough chronic total occlusions in the vasculature. The support andcentering functionality has application beyond CTOs, even though thepreferred embodiments described herein are directed to support andcentering to facilitate a guidewire to cross through a CTO.

In particular, embodiments of the invention may accomplish this with anapparatus for efficiently and effectively passing a microcatheterthrough the center of a chronic total occlusion in a vasculature. Inparticular, embodiments of the invention provide for apparatus andmethods for centering a microcatheter within a vasculature, and forsimplifying the insertion of multiple devices or microcatheters into thevasculature.

One embodiment of the invention is a catheter apparatus including: amicrocatheter having a lumen, a distal opening and a distal end; one ormore guidewires for passing through the lumen of the microcatheter; aninner shaft having a lumen, a distal opening and a distal end forallowing the microcatheter to pass through this inner shaft; an outershaft having a lumen, a distal opening and a distal end for passing theouter shaft over the inner shaft; and a substantially cylindricalself-expandable scaffold structure having a distal end and a proximalend disposed towards the distal end of the inner shaft, wherein theproximal end of the structure is attached to the inner shaft, whereinthe distal end is slidable along the shaft, and wherein the scaffoldstructure is configured so that the inner shaft runs through the centerof the scaffold and wherein the scaffold structure is configured to benon-occluding. The microcatheter and inner shaft may be capable of beingindependently operable. The self-expandable scaffold may include loops,which project inwardly from the cylindrical plane of the scaffold. Inone embodiment, the loops position the inner shaft approximately in thecenter of the cylindrical plane of the scaffold.

The self-expandable scaffold structure may be made from a variety ofmaterials including nitinol. In one embodiment, the self-expandablescaffold includes a loop network at the distal end of the scaffold.

The apparatus may also include a sleeve disposed on the distal end ofthe self-expandable scaffold. The sleeve may hold the self-expandablescaffold in place without attaching the scaffold to the inner shaft suchthat the inner shaft and scaffold are separated by a gap.

In one embodiment, the outer shaft and inner shaft are flexible. Inanother embodiment, the distal end of the outer shaft is hydrophilic.This property may be achieved by means of a coating. Thus, in oneembodiment, the distal end of the outer shaft includes a hydrophiliccoating.

The lumen of the inner shaft and/or outer shaft may be configured toaccommodate one or more guidewires. Thus, in one embodiment, the deviceincludes one or more guidewires, which pass through the microcatheter.The microcatheter may be removable and/or highly flexible.

In one embodiment, the distal end of the outer shaft is beveled andtapered. This structure at the distal end of the outer shaft may aidwith the proper positioning of the device in the vasculature.

The lumen of the inner shaft and/or outer shaft may be configured toaccommodate one or more guidewires. Thus, in one embodiment, the deviceincludes one or more guidewires in addition to the one or moreguidewires, which pass through the microcatheter. In one embodiment, thedistal end of the microcatheter is tapered. The microcatheter may beremovable and/or highly flexible. The catheter apparatus may alsoinclude a handle body.

Another embodiment of the invention is a catheter apparatus including: amicrocatheter having a lumen, a distal opening and a distal end; aninner shaft having a lumen, a distal opening and a distal end forpassing the inner shaft over the microcatheter; an outer shaft having alumen, a distal opening and a distal end for passing the outer shaftover the inner shaft; and a substantially cylindrical self-expandablescaffold structure having a proximal end and a distal end, disposedtowards the distal end of the inner shaft wherein the proximal end ofthe structure is attached to the inner shaft, wherein the distal end isslidable along the shaft, and wherein the scaffold structure isconfigured so that the inner shaft runs through the center of thescaffold and wherein the scaffold structure is configured to benon-occluding. Optionally, the catheter apparatus includes one or moreguidewires for passing through the lumen of the microcatheter and/or ahandle body. The microcatheter is capable of being independentlyoperable.

The self-expandable scaffold may include one or more loops, whichproject inwardly from the cylindrical plane of the scaffold. In oneembodiment, the loops position the inner shaft approximately in thecenter of the cylindrical plane of the scaffold. The self-expandablescaffold may be made from nitinol. Optionally, the self-expandablescaffold includes a loop network at the distal end of the scaffold. Asleeve may also be disposed on the distal end of the self-expandablescaffold. The sleeve holds the self-expandable scaffold in positionwithout attaching it to the shaft. The distal end of the scaffold may beseparated from the shaft by a gap.

In one embodiment, the outer shaft and inner shaft are flexible. Inanother embodiment, the distal end of the outer shaft is hydrophilic. Inyet another embodiment, the distal end of the outer shaft includes ahydrophilic coating.

The lumen of the inner shaft and/or outer shaft may be configured toaccommodate one or more guidewires. In one embodiment, the distal end ofthe outer shaft is beveled and tapered. In another embodiment, thedistal end of the microcatheter is tapered. The microcatheter may beremovable and/or highly flexible.

Yet another embodiment of the invention is a catheter apparatusincluding: a microcatheter having a lumen, a distal opening and a distalend; an inner shaft having a lumen, a distal opening and a distal endfor allowing the microcatheter to pass through this inner shaft; anouter shaft having a lumen, a distal opening and a distal end forpassing the outer shaft over the inner shaft; and one or moreself-expandable scaffold structures disposed towards the distal end ofthe inner shaft, wherein each of the one or more self-expandablescaffold structures includes a center band surrounding the inner shaftand one or more expansible arms attached to the center band. One of theone or more self-expandable scaffold structures may be on the distal endof the inner shaft. This scaffold may be configured to be non-occluding.The center band and/or arms of the scaffold may include one or moreopenings. Furthermore, the arms may curve. Preferably, microcatheter iscapable of being independently operable. The apparatus may be configuredto include a sleeve disposed on the distal end of the self-expandablescaffold (such as, e.g., over the center band). Alternatively, the ringmay be glued to the scaffold. The outer shaft and inner shaft may beflexible. The distal end of the outer shaft may be hydrophilic via,e.g., use of a hydrophilic coating. The lumen of the inner shaft and/orouter shaft may be configured to accommodate one or more guidewires. Thedistal end of the outer shaft may be beveled and tapered. The distal endof the microcatheters may also be tapered. The microcatheter may beremovable and/or highly flexible. The catheter apparatus may alsoinclude one or more guidewires for passing through the lumen of themicrocatheter and/or a handle body.

Another embodiment of the invention is a method of operating such acatheter. In one embodiment, the method includes providing a catheterapparatus of the invention; inserting a guide catheter into avasculature with a chronic total occlusion; inserting the catheterapparatus of into the guide catheter; advancing the catheter apparatusinto contact with the chronic total occlusion; translating the outershaft over self-expandable scaffold; allowing the self-expandablescaffold to expand; wherein the inner shaft is approximately centered onthe inside of the self-expandable scaffold; and advancing themicrocatheter apparatus into contact with the chronic total occlusion.In one embodiment, the inner shaft is approximately centered relative tothe vasculature.

Another embodiment of the invention is a catheter apparatus including: amicrocatheter having a lumen, a distal opening and a distal end; aninner shaft having a lumen, a distal opening and a distal end forpassing the inner shaft over the microcatheter; an outer shaft having alumen, a distal opening and a distal end for passing the outer shaftover the inner shaft; and a substantially cylindrical self-expandablescaffold structure having a proximal end and a distal end, disposedtowards the distal end of the inner shaft, wherein the proximal end ofthe structure is attached to the inner shaft, wherein the distal end isslidable along the shaft, and wherein the scaffold structure isconfigured so that the inner shaft runs through the center of thescaffold and wherein the scaffold structure is configured to benon-occluding. The catheter apparatus may further include one or moreguidewires for passing through the lumen of the microcatheter. The innershaft and microcatheter may be capable of being independently operable.In one embodiment, the self-expandable scaffold includes loops, whichproject inwardly from the cylindrical plane of the scaffold. The loopsmay position the inner shaft approximately in the center of thecylindrical plane of the scaffold. The self-expandable scaffold may bemade of nitinol. The self-expandable scaffold may also include a loopnetwork at the distal end of the scaffold. Optionally, the apparatus mayfurther include a sleeve disposed on the distal end of theself-expandable scaffold. The inner and outer shaft may be flexible. Inone embodiment, distal end of the outer shaft is hydrophilic. In anotherembodiment, the distal end of the outer shaft includes a hydrophiliccoating. The lumen of the inner shaft and/or outer shaft are configuredto accommodate one or more guidewires. The distal end of the outer shaftmay be beveled and tapered. For example, the distal end of themicrocatheter may be tapered. The microcatheter may highly flexibleand/or removable. The apparatus may also include a handle body.

Yet another embodiment of the invention is a catheter apparatusincluding a shaft having a lumen and one or more self-expandablescaffold structure disposed on the distal end of the end shaft, whereinthe scaffold when expanded centers the lumen of the shaft. The apparatusmay include one or more self-expandable scaffold structure. In certainembodiment, the self-expandable scaffold structure is substantiallycylindrical, has a distal end and a proximal end and the proximal end isdisposed towards the distal end of the inner shaft. In certainembodiments, the self-expandable scaffold structure includes loops,which project inwardly from the cylindrical plane of the scaffold. Theinward facing loops may be attached to the scaffold. The shaft may passthrough the loops. In one embodiment, the self-expandable scaffoldstructure is substantially cylindrical, has a distal end and a proximalend, wherein the distal end is crimped and the proximal end is disposedtowards the distal end of the inner shaft. In another embodiment, theself-expandable scaffold structure is substantially cylindrical, has adistal tip and a proximal end, wherein the distal tip is configured forpassing the shaft and wherein the proximal end is disposed towards thedistal end of the inner shaft. In certain embodiments, theself-expandable scaffold does not include loops, which project inwardlyfrom the cylindrical plane of the scaffold. In one embodiment, each ofthe one or more self-expandable scaffold structures includes a centerband surrounding the inner shaft and one or more expansible armsattached to the center band.

Another embodiment of the invention is a method of centering amicrocatheter in vessel including: inserting a microcatheter having oneor more self-expandable scaffold structure towards the distal end of themicrocatheter in a vessel, wherein the self-expandable scaffoldstructure is covered by an outer shaft, and withdrawing the outer shaftto expand the self-expandable scaffold structure whereby expansion ofthe scaffold centers the microcatheter. In certain embodiments, themicrocatheter includes one self-expandable scaffold structure. Theself-expandable scaffold structure may be substantially cylindrical, hasa distal end and a proximal end and wherein the proximal end is disposedtowards the distal end of the microcatheter. In another embodiment, theself-expandable scaffold structure includes loops, which projectinwardly from the cylindrical plane of the scaffold. The inward facingloops may be attached to the scaffold. The shaft may pass through theloop. In certain embodiments, expansion of the scaffold centers themicrocatheter inside scaffold thereby approximately centering themicrocatheter in the vessel. In one embodiment, the self-expandablescaffold structure is substantially cylindrical, has a distal end and aproximal end, wherein the distal end is crimped and wherein the proximalend is disposed towards the distal end of the inner shaft. In anotherembodiment, the self-expandable scaffold structure is substantiallycylindrical, has a distal tip and a proximal end, wherein the distal tipis configured for passing the shaft and wherein the proximal end isdisposed towards the distal end of the inner shaft. In certainembodiments, the self-expandable scaffold does not include loops whichproject inwardly from the cylindrical plane of the scaffold. In certainembodiments, expansion of the scaffold may center the microcatheterinside scaffold thereby approximately centering the microcatheter in thevessel. In another embodiment, each of the one or more self-expandablescaffold structures includes a center band surrounding the inner shaftand one or more expansible arms attached to the center band.

Another embodiment of the invention is a catheter apparatus including: ahollow shaft with a distal end and a proximal end, and a non-occludingself-expandable scaffold having a central longitudinal axis, theself-expandable scaffold being disposed at the distal end of thecatheter, wherein a portion of the distal end of the catheter isdisposed at least in part inside the self-expandable scaffold, whereinthe distal end is slidable along the shaft, and wherein the scaffold isconfigured to be coupled to the distal end of the catheter, wherein atleast a portion of the distal end of the catheter is disposedsubstantially along the central axis of the self-expandable scaffoldstructure. The catheter apparatus may further include a sheath forsliding over the hollow shaft. The catheter apparatus may also furtherinclude a microcatheter having a lumen, a distal opening, and a distalend. In one embodiment, inner shaft and microcatheter are capable ofbeing independently operable. In another embodiment, the microcatheterincludes comprising one or more guidewires for passing through the lumenof the microcatheter. The microcatheter may be more rigid and lessflexible than the one or more guidewires. The self-expandable scaffoldincludes loops which project inwardly from the cylindrical plane of thescaffold to the central longitudinal axis of the self-expandablescaffold structure. In certain embodiments, the loops position the shaftapproximately along the central longitudinal axis of the self-expandablescaffold structure. The self-expandable scaffold may be made of nitinol.The self-expandable scaffold may also include a loop network at thedistal end of the scaffold. The sheath and shaft may be flexible. Thedistal end of the shaft may be hydrophilic. Alternatively, the distalend of the sheath includes a hydrophilic coating. In one embodiment, thedistal end of the microcatheter is tapered. In another embodiment, themicrocatheter is removable or highly flexible. The catheter apparatusmay also include a handle body.

Yet another embodiment of the invention is a method of centering amicrocatheter in vessel comprising: inserting a microcatheter intovessel, wherein the microcatheter includes a hollow shaft with a distalend and a proximal end, a non-occluding self-expandable scaffold havinga central longitudinal axis, the self-expandable scaffold being disposedat the distal end of the catheter, wherein a portion of the distal endof the catheter is disposed at least in part inside the self-expandablescaffold, and a sheath wherein the distal end is slidable along theshaft, wherein the scaffold is configured to be coupled to the distalend of the catheter, wherein at least a portion of the distal end of thecatheter is disposed substantially along the central axis of theself-expandable scaffold structure, wherein the hollow shaft is coveredby the sheath; and withdrawing the sheath to expand the self-expandablescaffold structure whereby expansion of the scaffold centers themicrocatheter along the central longitudinal axis of the scaffoldthereby centering the microcatheter in the vessel. In certainembodiments, the microcatheter may be a microcatheter as describedabove. In one embodiment, the method also includes inserting a guidewirethrough the microcatheter. In one embodiment, the vessel has a chronicocclusion and the method further includes advancing the microcatheter incontact with the chronic occlusion. In certain embodiments, theself-expandable scaffold includes loops, which project inwardly from thecylindrical plane of the scaffold to the central longitudinal axis ofthe self-expandable scaffold structure. The loops may position the shaftapproximately along the central longitudinal axis of the self-expandablescaffold structure.

Another embodiment is a method of treating a chronic total occlusionwith a catheter apparatus of the invention. In one embodiment, the innershaft is approximately centered relative to the vasculature.

Embodiments of the present invention may incorporate several features tosuccessfully center a microcatheter in a chronic occlusion. Features ofthe present invention may include a catheter apparatus comprising anouter shaft having a lumen, an inner shaft having a lumen, amicrocatheter having a lumen, one or more guidewires for passing throughthe lumen of the microcatheter and a scaffold structure whereby thescaffold structure is attached to the inner shaft, and whereby the innershaft and microcatheter telescope independently of each other. Thescaffold is configured to be non-occluding, allowing blood to flowthrough. Features of the present invention also include expansion oractivation of a distal tip for creating a scaffold structure.

The apparatus of the invention are able to mitigate deflection of theguidewire tip in a vessel during treatment of a chronic total occlusion.In particular, the distal end of the microcatheter serves to protect andprovide support, such as stable or rigid support, for the one or moreguidewires. In certain embodiments, the microcatheter may act anindependent guidewire support.

The devices of the invention offers a simple and stable platform fromwhich clinicians can effectively treat these challenging chronic totalocclusion lesions with a guidewire of their choice. Using nitinolscaffolding and a centering core lumen, the catheter may provideinterventionalists a stable entry point into the true lumen. In certainembodiments, self-expanding scaffolding (e.g. made of nitinol) providesfor anchoring at the lesion. In particular, the anchoring may beatraumatic and non-occlusive. Devices of the invention provide for areliable centering access of the guidewire. Moreover, the configurationof devices of the invention allow for co-axial alignment such that thelumen of the device (and therefore the guidewire) is centrally alignedwith the CTO cap.

In certain embodiments of the invention, the devices of the inventionprovide for non-occlusive anchoring (via the self-expandable scaffold).The devices of the invention also provide for complete support of theguidewire. Due to the configuration, the operation of the device issimple and repeatable. Thus, the devices of the invention may be used inan antegrade approach.

FIGS. 1A and 1B show exemplary embodiments of a proximal end of acatheter system in accordance with the principles of the invention. Thedistal end of the system is not shown in these figures and can embodythe various embodiments described and shown in the figures anddescription described herein and subsequently.

FIG. 1A shows a partial break-away view of a proximal end of a catheterapparatus according to one embodiment of the invention. The proximal endincludes a handle body 100A. Handle body 100A of the catheter apparatusincludes a lumen through which outer shaft 110 can pass. The outer shaftmay be attached the handle. The outer shaft also includes a lumen thoughwhich inner shaft 120 may pass. Inner shaft 120 has a lumen throughwhich one or more microcatheter (not shown) may pass and inner shaft 120extends distally to be associated with a scaffold (not shown); both themicrocatheter and the scaffold are discussed in more detail in thefollowing description and figures. Toward the proximal end of handlebody 100A is hemostasis valve 140. Towards the distal end of the handle100 is thumb lever 115. The thumb lever 115 may be adjustable. In oneembodiment, thumb lever 115 is may be adjustable to hold outer shaft 110in place.

Tip 105 may be located at the distal end of handle body 100A. In oneembodiment, the tip 105 provides for a step-wise taper. Alternatively,the tip 105 provides gradual taper. In one embodiment, the taper servesto provide strain relief on the handle. In one embodiment, the tip endis integral with the outer shaft assembly 125. In another embodiment ofthe invention, the tip is integral with the handle body 100A.

Outer shaft assembly 125 is located toward the distal end of handle body100A. Outer shaft assembly 125 extends from the proximal end of handlebody 100A into the interior. Outer shaft assembly 125 may be integralwith handle body 100A. Thumb lever 115 may be connected to the outershaft assembly 125.

The outer shaft 110 and/or inner shaft 120 may be surrounded by aninternal reinforcement shaft 135. The internal reinforcement shaft 135may extend from approximately the proximal end to approximately distalend of the handle body 100A. In one embodiment, the reinforcement shaftextends the entire length of the handle body 100A. In anotherembodiment, the reinforcement shaft 135 only extends to the outer shaftassembly 125. In an alternate embodiment, the reinforcement shaft 135extends into or through the outer shaft assembly 125. Reinforcementshaft 135 may be integral with the handle body 100A. Reinforcement shaft135 may be a rigid tube that surrounds the outer shaft 110 and/or innershaft 120. In one embodiment, the proximal end of the outer shaft islocated at proximal end of the outer shaft assembly 125. The internalreinforcement shaft 135 is adjacent to or connected to the proximal endof outer shaft assembly 125. The inner shaft 120 passes through theinternal reinforcement shaft 135 and then through the outer shaft 110.The internal reinforcement shaft 135 may be configured so that itprevents buckling of the inner shaft 120. Furthermore, the length andconfiguration of the internal reinforcement shaft 135 may vary dependingon the contemplated use. The internal reinforcement shaft 135 may spanall or part of the entire length of the handle body 100A.

FIG. 1B shows another view of a handle of a catheter apparatus accordingto one embodiment of the invention. Handle body 100B of the catheterapparatus includes a lumen through which outer shaft 110 (not shown) canpass. The outer shaft may be attached the handle. The outer shaft alsoincludes a lumen though which inner shaft 120 may pass Inner shaft 120has a lumen through which one or more microcatheters (for example, FIG.4, microcatheter 130) may pass. Each of the one or more microcathetershas a lumen through which one or more guidewires may pass. The handlefurther includes hemostasis valve 140, which is located at the proximalend of the body, and inner lumen flush 122. A microcatheter 130 may beinserted through the proximal end of handle body 100B. The hemostasisvalve 140 may be adjustable to hold microcatheter 130 in place. Innerlumen flush 122 may be connected to the lumen of inner shaft 120 Innerlumen flush 122 may be positioned towards the proximal end of the handlebody 100B. The handle body 100B may also include thumb lever 115, whichmay be positioned towards the distal end of the handle body 100B.

With reference to FIG. 1A and FIG. 1B, the handle body (100A/100B) isconfigured with a lumen through which outer shaft 110 passes. Outershaft 110 in turn is configured with a lumen through which inner shaft120 passes. The one or more microcatheter 130 (as shown, e.g., in FIG.1B) in turn passes through the inner shaft 120. The outer shaft 110,inner shaft 120, and microcatheter 130 may be slideably operableindependently of each other. Thus, the inner shaft 120 may telescope inand out of the outer shaft 110 and the one or more microcatheter 130 maytelescope in and out of the inner shaft 130. Furthermore, when one ormore guidewires 132 is used in conjunction with microcatheter 130, theone or more guidewires 132 may be slideably operable independently ofthe outer shaft 110, inner shaft 120, and microcatheter 130. The one ormore guidewires 132 may telescope in and out of the microcatheter 130.

The outer shaft 110 may be configured to act as a sheath. The innershaft 120 and outer shaft 110 may be flexible and roughly of cylindricalshape and/or having a generally circular transvers cross-section. Thehandle body may be made of a rigid plastic material.

In one embodiment, the apparatus includes an outer shaft having a lumen,an inner shaft having a lumen, a microcatheter having a lumen, ascaffold structure and one or more guidewires. The outer shaft isconfigured to allow passage of the inner shaft through lumen of theouter shaft. The microcatheter passes through the lumen in the innershaft and the one or more guidewire in turn pass through the lumen ofthe microcatheter shaft. The scaffold structure may be attached to theinner shaft towards or on the distal end of the inner shaft 120.

The scaffold structure provides anchoring support and may benon-occlusive, allowing blood flow to collateral and branch vessels.While the scaffold structure may be self-expanding, scaffold structuressuitable for use in the devices of the invention are not limited toself-expanding scaffold structures. Preferably, the scaffold structurehas a broad working range (i.e., one size fits all). The scaffoldstructure may also be tailored for the specific intended uses. Thescaffold structure may alone, and/or in combination with otherstructures and/or features to position the catheter device in the arteryand to position the one or more microcatheters substantially centered inthe middle of the scaffold/artery.

The scaffold structure may have a centering element, e.g., a mechanismto support an internal lumen and/or catheter or microcatheter away fromthe vessel wall. The scaffold structure may be atraumatic to the vesselwall thereby requiring minimal hoop strength to maintain position. Thescaffold structure is configured to re-sheath to facilitate withdrawaland can be employed multiple times. The scaffold may be removable andused temporarily for reliable positioning and centering, preferably, forpositioning and centering of a microcatheter. The scaffold preferably isof a quality and construction for being temporarily deployed in thevasculature, for anchoring in the vasculature, for being removable fromthe vasculature and/or for being redeployed in the vasculature. Thescaffold, although it may be of implantable quality and construction, itis not intended to be used as an implant or an implantable device thatremains in the vasculature after use, for example, for crossing alesion.

FIG. 2A shows a partial cross-sectional view of the distal design of acatheter apparatus according to one embodiment of the invention in itsexpanded state without a microcatheter. In one embodiment, the catheterapparatus of FIG. 2A includes handle body 100, which may be configuredas illustrated above. In another embodiment, the catheter apparatus ofFIG. 2A may not include handle body 100. The catheter apparatus mayfurther include one or more microcatheters.

With reference to FIG. 2A, the distal design of the catheter apparatusincludes an inner shaft 120 having a lumen, a distal opening and adistal end; an outer shaft 110 having a lumen, a distal opening and adistal end for passing the outer shaft 110 over the inner shaft 120 anda self-expandable scaffold 145 disposed towards or attached towards thedistal end of the inner shaft 120. Preferably, the self-expandablescaffold structure 145 has a proximal end 155 and distal end 157. Theapparatus may also have a distal tip 150. Distal tip 150 may vary inconstruction and hardness. In one embodiment, distal tip 150 may besoft. The distal tip 150 is attached to the scaffold structure 145.Preferably, the scaffold structure 145 is self-expanding. FIG. 2A showsscaffold 145 in an expanded position. The proximal end 155 ofself-expandable scaffold 145 is disposed or attached (e.g. fixed) to theinner shaft 120, as shown, at a distal end of the inner shaft 120.Preferably, the distal end 157 or distal tip 150 of the scaffold 145 isnot attached to the inner shaft 120, for example, the scaffold 145 isslidably attached to the inner shaft 120. Although, if desired thedistal tip 150 may be attached to the outer shaft depending on thescaffolding and use of the device. The distal end 157 of the scaffold145 may be crimped. The distal end 157 of scaffold structure 145 may beheld in place by a ring, for example, of the types and kinds describedand shown with respect to FIG. 2B, at reference numeral 170, withoutbeing fixed to the inner shaft 120 thereby allowing the ring to move andslide back and forth longitudinally. The ring 170 can slide relative toshaft 120. In an alternate embodiment, the distal tip of the scaffoldmay be folded over so that the distal tip may be oriented toward theproximal end 155 as described herein and shown in FIGS. 6 and 11B. Thering 170 may be slid over the folded over distal tip of this alternateembodiment, although not shown in the figures.

The outer shaft 110 may include position detection marker 160 towardsthe distal end of the outer shaft. The detection marker 160 may be aradio-opaque marker band. Markers can also be provided elsewhere, forexample, markers can be provided on the inner shaft 120 and/or themicrocatheter 130.

The outer shaft may also have distal tip 162 on the distal end of theouter shaft 110. The distal tip 162 of the outer shaft 110 may bebeveled and/or rounded. As shown, the end of the outer shaft 110 isbeveled as shown at 161 and is curved at 163. This may aid in thedelivery and/or positioning of the system. For example, thisconfiguration may aid in preventing deflection away from the fibrous captowards the adventitial layer, and thereby may aid in the prevention ofthe device entering a false lumen. Alternatively, the distal tip of theouter shaft may be tapered, beveled, round or combinations thereof.

The outer shaft 110 may have a hydrophilic coating on the distal end.The outer shaft may have a diameter of about 0.062 inches. The lumen ofthe outer shaft may have a diameter of about 0.054 inches. When in use,the outer shaft translates to cover and uncover self-expandable scaffoldstructure 145. As such, the scaffold can exit out of and be refractedinto outer shaft 110.

The inner shaft 120 may be in a fixed position relative to handle body100. The inner shaft 120 may be in tubular shape to allow effectivecommunication to a distal vessel. The minimum diameter of the lumen ofthe inner shaft 120 may be about 3 French. Alternatively, the diameterof the inner shaft may be from about 0.045 to about 0.050 inches. Theinner shaft may be configured to be compatible with one or moremicrocatheters and/or guidewires. In one embodiment, the inner shaft maybe configured to be compatible with a guidewires about 0.038 inches indiameter. The inner shaft is preferably approximately centered relativeto the self-expandable scaffold structure 145.

Preferably, the inner shaft 120 is configured to be flexible,lubricious, and kink-resistant. In one embodiment, the inner shaft 120is configured to be compatible with a microcatheter, which is compatiblewith guidewires about 0.014 to about 0.018 inch. The inner shaft ispreferably affixed to a proximal handle (such as, e.g., handle body100). But, inner shaft 120 may not be fixed so it can be movedindependently as well.

The outer shaft 110 and inner shaft 120 may be slideably operableindependently of each other. Thus, the inner shaft may telescope in andout of the outer shaft. Furthermore, the lumens of the inner and outershaft may be configured to accommodate one or more guidewires. The oneor more guidewires may also telescope independently from the outer andinner shaft.

FIG. 2B shows a view of the distal design of a catheter apparatusaccording to one embodiment of the invention in its expanded state withthe microcatheter 130 in place. In one embodiment, the catheterapparatus of FIG. 2B includes handle body 100 as illustrated above. Inanother embodiment, the catheter apparatus of FIG. 2B may include otherproximal apparatus and/or handle(s), as discussed further below.

The catheter apparatus includes a microcatheter 130 having a lumen, adistal opening and a distal end; one or more microcatheter guidewires132 for passing through the lumen of the microcatheter 130; an innershaft 120 having a lumen, a distal opening and a distal end for passingthe inner shaft 120 over the microcatheter 130; an outer shaft 110; anda self-expandable scaffold 145 structure disposed towards or attachedtowards the distal end of the inner shaft 120.

As shown in FIG. 2B, outer shaft 110 has a lumen through which innershaft 120 passes. Inner shaft 120 in turn has a lumen through whichmicrocatheter 130 passes. The microcatheter also has a lumen throughwhich one or more guidewires passes. In a preferred embodiment, only oneguidewire 132 passes through the lumen of the microcatheter. The outershaft 110, inner shaft 120, and microcatheter 130 may be slideablyoperable independently of each other. Thus, the inner shaft 120 maytelescope in and out of the outer shaft 110 and the microcatheter 130may telescope in and out of the inner shaft 120. Furthermore, one ormore guidewire 132 may telescope independently of the inner shaft 120,outer shaft 110, and/or microcatheter 130. The microcatheter 130 andguidewire 132 may be advanceable as a group. Alternatively, themicrocatheter 130 and guidewires 132 may be individually advanceable.

Preferably, the proximal end of the scaffold structure is attached tothe inner shaft 120. The proximal end of the scaffold may be physicallyattached to the inner shaft 120. The proximal end of the scaffold may beheld in place by a biologically acceptable glue or a fitting. Thefitting would slide over the proximal end of the scaffold and hold it inplace. The fitting, as shown, may include a ring 170 positioned aroundthe distal end of the scaffold structure 145 without attaching orfixedly securing the scaffold structure 145 to the inner shaft 120.Thus, the distal end of the scaffold is slidable.

The outer shaft 110 may include position detection marker 160 towardsthe distal end of the outer shaft. In one embodiment, the positiondetection marker 160 is a marker band such as, e.g., a radiopaquemarker. The distal end of the outer shaft 110 may be beveled androunded.

The microcatheter 130 may also include one or more position detectionmarkers 165. The position detection marker 165 may be a marker band suchas, e.g., a radiopaque marker. The inner shaft may also include markers,not shown.

The microcatheter 130 may include a tapered tip at the distal end. Thetip may be soft. Alternatively, the hardness may vary. The microcatheter130 is independently movable from the inner shaft 120 and may beremovable. Preferably, the microcatheter 130 translates independentlywithin the lumen of inner shaft 120. The microcatheter 130 has a lumenthrough which a one or more guidewires may pass. The microcatheter 130may have a lumen with an internal diameter of about 0.017 to about 0.021inches. The microcatheter may have an outer diameter of about 2.1 Frenchat the tip and an outer diameter of about 2.5 French proximal to thetaper. Furthermore, the microcatheter may be highly flexible and mayhave a low profile (<3 French) as well as a soft distal tip.

The microcatheter 130 can advance beyond the distal end of the innershaft 120 to support a guidewire 132, which is advanced through thelesion. Thus, the microcatheter 130 is able to provide structuralrigidity and/or support to the guidewire by protecting it fromunnecessary bending. In a preferred embodiment, the microcatheter isharder and/or has more column strength than the guidewire. The reliablycentered microcatheter and guidewire passing through the microcatheterallows for targeted central access to the lesion and/or occlusion. Theability to translate both the microcatheter and/or the guidewiretogether and independently allows for controlled variable engagementwith the lesion and/or occlusion. The differing hardness/softnessbetween the microcatheter and the guidewire also allows for variedengagement with the lesion and/or occlusion.

The microcatheter 130 also may serve as an extension to the scaffold.The microcatheter may be extended distally beyond the distal end of thedeployed/anchored scaffold, yet the microcatheter remains reliablycentered as a result of the scaffold. The centered extendedmicrocatheter extends the centering capability of the system distallyfrom the scaffold to center the guidewire further distally.

The components of the catheter apparatus of the invention have varyingdegrees of rigidity. Preferably, the rigidity and/or support increasesgoing from the microcatheter guidewires 132 to the microcatheter 130.The rigidity and/or support also increases going from the microcatheter130 to the inner shaft 120. The rigidity and/or support furtherincreases going from the inner shaft 120 to the outer shaft 110. Thehandle body 100 has the highest degree of rigidity. In other words, in apreferred embodiment, the microcatheter is more rigid and has morecolumn strength than the guidewire. The inner shaft is more rigid andhas more column strength than the microcatheter, and therefore theguidewire, too. The outer shaft is more rigid and has more columnstrength than the inner shaft.

The outer shaft, inner shaft, and microcatheter may be made of aflexible plastic material or any other substance or materials asappropriate to accommodate curves, bends and tortuosity in thevasculature, for example.

The position detection marker 160 and marker 165 may be simpleradiopaque markers. With radiopaque marking, users may improve theirability to identify the location of the distal end of the catheter andmicrocatheter during a procedure.

FIG. 2C is a partial view of one embodiment of the self-expandablescaffold 145 structure at the distal end of a catheter apparatus shownin FIG. 2A. With reference to FIG. 2C, the arrangement of expandablescaffold structure 145 on inner shaft 120 is shown. As discussed above,the inner shaft 120 has a lumen through which microcatheter may pass.The proximal end 155 of self-expandable scaffold 145 is disposed orattached (e.g., fixed) to the inner shaft 120. The distal tip 150 isdisposed or attached (e.g., fixed) to the distal end 157 of scaffold145. As shown, the distal end 157 and distal tip 150 are not attached tothe inner shaft 120. Gap 161 separates the scaffold structure 145 fromthe inner shaft 120. In one embodiment, the distal end 157 and/or distaltip 150 are held in place by a ring 170 while maintaining gap 161. Thering 170 is mounted on distal end 157. In an alternate embodiment, notshown in FIG. 2C, the distal tip 150 may be folded over so that thedistal tip 150 is oriented towards the proximal end 155 and the ring 170may be slid over the folded over distal tip.

Scaffold structure 145 may be self-expandable. The proximal end 155 ofthe scaffold structure 145 is preferably physically attached to theinner shaft 120, preferably, fixedly attached and, more preferably,fixedly attached to prevent any substantial movement relative to shaft120. As discussed above, the proximal end of the scaffold may be held inplace by a biologically acceptable glue or a fitting. The scaffold istowards the distal end of the inner shaft 120. In one embodiment, theproximal end 155 may be attached to the inner shaft 120. In oneembodiment, the scaffold structure 145 is configured such that outershaft 110 can slide over the self-expandable scaffold structure 145 andthereby collapse the scaffold. In one embodiment, the self-expandablescaffold structure 145 is retractable into the outer shaft 110.

The scaffold structure 145 creates a substantially tube-like and/orcylindrically-shaped structure. It is configured in such a way that theinner shaft 120 (and therefore microcatheter 130 and guidewire) passthrough approximately the center of the scaffold. Preferably, theself-expandable scaffold structure is substantially cylindrical. In oneembodiment, the inner shaft 120 (and therefore microcatheter 130 andguidewire) passes through the center of the scaffold. In anotherembodiment, when in operation, the inner shaft 120 (and thereforemicrocatheter 130) passes through the center of the scaffold and thecenter of the vasculature. This configuration allows for reliablepositioning in the vasculature for center access to the CTO. Inparticular, the distal end opening of the inner shaft and the distal endopening of the microcatheter are positioned, disposed, and/or centeredon the central longitudinal axis of the anchored scaffold, thereforeproviding reliable central access to the lesion and/or CTO. Thescaffold, inner shaft and microcatheter in various combinations,reliably center the system for centered positioning of the guidewire andfor translation of the shaft, microcatheter and guidewire to cross thelesion and/or CTO at the center.

The self-expandable scaffold structure 145 may be in a cellularconfiguration. In another embodiment, the scaffold structure may beconfigured as a lattice. Various patterns may be used in accordance withthe principles of the invention. The self-expandable scaffold structure145 may preferably be configured to be non-occluding thereby allowingblood to flow through during the procedure. The vasculature is notoccluded with the system described herein. In another configuration, thescaffold structure may be composed of braided wires. Nitinol and/orstainless steel may be incorporated into the self-expandable scaffoldstructure 145. Nitinol is an illustrative example of a shape memoryalloy. Other shape memory alloys or other similar substances may beused. Generally, after a sample of a shape memory alloy has beendeformed from its original crystallographic configuration, the shapememory alloy regains its original geometry by itself. This property ofshape memory alloys may allow for expansion of the self-expandablescaffold structure 145 after telescoping from the outer shaft 110. Thenitinol and/or stainless steel self-expandable scaffold structure 145may create a stent-like mesh.

A self-expanding polymer may fill the interior portion ofself-expandable scaffold structure 145. In an initial configuration, theself-expanding polymer may be in a compressed state. As the scaffoldstructure slideably expands by movement of the inner shaft, theself-expanding polymer may expand as well. The self-expanding polymermay expand by absorbing moisture or blood from within the vasculature orthrough other expansion mechanisms.

In one embodiment, the scaffold is about 20 mm in length whencompressed. When fully expanded the scaffold length may decrease. In oneembodiment, the scaffold may be incrementally expandable in incrementsfrom about 2.0 mm to about 5.0 mm. The scaffold may position the innershaft 120 and microcatheter 130 so that they are approximately centeredrelative to the chronic total occlusion.

The catheter apparatus may further include one or more guidewires. Thelumen of the inner shaft, the outer shaft, or both may be configured toaccommodate guidewires. The one or more guidewires may be passed throughthe chronic total occlusion using the system described herein.

The catheter apparatus may be withdrawn from the vasculature whileleaving the one or more guidewires in place (including the one or moreguidewires to pass through the lumen of the microcatheter). The scaffoldstructure may be repositioned repeatedly until a suitable site forpassing the guidewire and/or microcatheter through the chronic totalocclusion is found. According to some embodiments discussed furtherbelow, one or more of the guidewire(s), microcatheter, and inner shaft,including the scaffold, may be withdrawn from the vasculature whileleaving the outer shaft in place. Thus, guidewires, the inner shaft andscaffold, microcatheters, or other instruments or catheters may beinserted into the vasculature through the outer shaft that was left inplace. In this way, the outer shaft may be used as a guide catheter.

Standard off-the-shelf or customized guidewires may be used. Forexample, in addition to traditional guidewires, embodiments of thepresent invention may be used with guidewires including, but not limitedto, steerable, hydrophilic, Teflon-coated, heparin-coated, ball-tip,J-tip, spiral tip, angulated wire and others.

Embodiments of the present invention may deliver energy via themicrocatheter through radio frequencies and/or lasers. Furthermore,other types of energy may be delivered such as direct conductive heatenergy, infrared or other types of energy that may be useful inparticular applications. Various types of microcatheters and/ordelivering energy via microcatheters may allow for various types oftreatments.

The external diameter of a catheter apparatus of the present inventionmay allow passage through a standard guide catheter. The outer surfaceof a catheter apparatus of the present invention may be coated withhydrophilic material to allow easier passage through the guide catheter.With alternate dimensions, a catheter apparatus of the present inventionmay be used in peripheral vessels. In this situation, a guide cathetermay not be necessary to insert the device into the vasculature.

The conversion of the scaffold 145 from its unexpanded to expanded statecreates a reasonably stable platform for advancing the inner shaft,microcatheter and one or more guide wires through the center of theocclusion. The expanded scaffold may be substantially cylindrical or ahollow tube. In certain embodiments, the activated scaffold 145 mayachieve other forms as well.

To achieve the expanded state shown in FIGS. 2A and B, the collapsedcatheter apparatus is expanded. In this collapsed configuration, theself-expandable scaffold structure 145, which is attached to inner shaft120 towards or on the distal end, is positioned inside the outer shaft110 between outer shaft 110 and inner shaft 120. Microcatheter 130 ispositioned inside the inner shaft 120 when desired and can be preloaded.The guidewire in turn is positioned inside the microcatheter whendesired and can be preloaded. The collapsed catheter apparatus may beadvanced over one or more guidewires with the outer shaft in place toconstrain the self-expanding but unexpanded self-expandable scaffoldstructure 145. The outer shaft 110 may cover the self-expandablescaffold structure 145. When the unexpanded scaffold structure isproperly positioned, the outer shaft may be retracted. As the outershaft 110 is retracted, the unexpanded self-expandable scaffoldstructure 145 expands to a substantially cylindrical or hollow tubeshape and may flare out. During the expansion process, the unexpandedscaffold structure may self-expand to assume a larger diameter toroughly approximate the diameter of a vasculature. The microcatheter 130may telescope along with the inner shaft 120 or separately.

The outer shaft 110 may be retracted to a stop point. The stop point mayprevent over-retraction of the outer shaft 110. Maintaining the positionof the outer shaft 110 at the stop point may facilitate re-sheathing(i.e. collapsing) the self-expandable scaffold structure 145.

The catheter devices and systems in accordance with the principles ofthe invention allow for gentle expansion to the artery wall/gentleengagement with the vasculature by anchoring of the scaffold, scaffoldpositioning of the shaft(s) and/or microcatheter, the individuallyindependently telescoping outer shaft, inner shaft and microcatheter,and the differing rigidity/softness relationships among the scaffold,shaft(s) and microcatheter. In particular as the self-expandablescaffold expands and presses against the walls of the vessel toapproximately center the inner shaft relative to occlusion. Preferably,the distal opening of the inner shaft is positioned at the center of theCTO in the vasculature. Preferably, the distal opening of themicrocatheter is positioned at the center of the CTO in the vasculature.The scaffold holds the device in place while the one or more catheters,preferably microcatheters, and/or guidewires are able to translate. Thescaffold preferably anchors in close proximity to the CTO so that themicrocatheter and the guidewire contact the CTO at the CTO's center.Furthermore, the devices of the invention are also unique in that theself-expandable scaffold structure is preferably non-occluding allowingblood to flow through.

Thus, another embodiment of the invention is a method of treatingvasculatures such as, e.g., chronic total occlusion of a vasculature byproviding a catheter apparatus of the invention in its collapsed state,positioning the collapsed catheter apparatus close to the site ofocclusion, expanding the collapsed catheter apparatus such that thedevice expands in the occlusion, telescoping the inner shaft and/ormicrocatheter and advancing the guidewire through the occlusion. Inparticular, the devices of the invention are prepared for use bycollapsing the scaffold structure. The self-expandable scaffoldstructure may be collapsed by sliding the outer shaft over it byactuating a thumb lever to retract the scaffold. In some embodiments,the scaffold structure may be collapsed by sliding the outer shaft overit by moving the proximal end of the out shaft relative to the proximalend of the inner shaft. The tip of the device is delivered to the targetlocation. The outer shaft is then retracted, allowing the self-expandingscaffold structure to expand naturally up to the vessel diameter. Oncethe self-expandable scaffold is expanded, the inner shaft is centeredinside the self-expandable scaffold and, therefore, the inner shaft iscentered in the vessel. This allows for reliable central positioningrelative to the CTO, lesion, and/or fibrous cap, thereby providing themicrocatheter and guidewire optimal access, control, alignment, andreliability to cross and/or pass the lesion.

Generally, after crossing a chronic total occlusion with a guidewire,the catheter apparatus may be resheathed and removed from thevasculature. The guidewire and/or microcatheter may be left in position.In some embodiments, the outer shaft may be left in position afterremoval of one or more of the guidewire, microcatheter, and inner shaft.

The positioning of the guidewire reliably in the center may optimize theforce of the guidewire when engaged with the fibrous cap of the chronictotal occlusion. The mass, rigidity, hardness, softness, strength and/orconstruction of the catheter apparatus, shaft(s) and/or themicrocatheter, and/or combinations thereof, may provide additionalsupport for the microcatheter and/or guidewire and prevents off-axis,i.e., lateral, displacement of the microcatheter and/or guidewire in thevasculature. Concentric placement of the microcatheter and/or guidewiremay allow for reliable central access to the fibrous cap despite theanatomy and/or tortuosity of the anatomy. FIG. 3 shows a view of thedistal configuration of a catheter apparatus according to anotherembodiment of the invention in its expanded state. The distalconfiguration of the device includes outer shaft 180, an inner shaft184, a self-expandable scaffold 186, a sleeve 188, a microcatheter 190,and a guidewire 192. The outer shaft has a lumen, a distal opening, anda tip 182 on the distal end. The inner shaft 184 also has a lumen, adistal opening, and a distal end. The microcatheter 190 also has adistal opening and a lumen. As is shown in FIG. 3, the device isflexible to allow the device to more through bends in arteries.

The outer shaft 180 is configured to allow passage of the inner shaft184 through the lumen of the outer shaft. The inner shaft 184 isconfigured to allow passage of the microcatheter 190 through the lumenof the inner shaft. The microcatheter 190 is configured to allow passageof guidewire 192 through the lumen of the inner shaft. In oneembodiment, the device includes one guidewire although multipleguidewires may be used serially or simultaneously.

The distal end of the outer shaft 180 has a distal tip 182. The distaltip 182 may be configured with a beveled end and/or a bend. For example,the outer shaft 180 may have two parallel longitudinal axes running fromopposing sides of the lumen of the outer shaft 180. One longitudinalaxis passes through the distal tip 182 and the other longitudinal axispasses through the opposite end of the outer shaft 180. The distal endof the outer shaft 180 may be tapered toward the one longitudinal axis.

The self-expandable scaffold 186 is attached to the inner shaft at theproximal end 194. Preferably, this attachment is fixed and notsubstantially moveable or slidable.

The inner shaft 184 may have a sleeve 188 attached towards the distalend of the inner shaft 184. Sleeve 188 is placed over the distal end ofthe scaffold structure 186 without fixedly attaching the scaffoldstructure 186 to the shaft 184. Sleeve 188 is preferably slidablerelative to the inner shaft 184. Preferably, expansion of theself-expandable scaffold structure 186 pushed up against sleeve 188 suchthat it holds the sleeve 188 in place.

Various microcatheters may be used with the devices of the invention.FIG. 4 shows a distal end of a microcatheter 130 that may be used withthe devices of the invention. Specifically, microcatheter 130 is shownwith optional position detection marker 165. In certain embodiments, themicrocatheter may have a single lumen. For example, as shown in FIG. 4,guidewire 132 may pass through the single lumen of microcatheter 130. Incertain embodiments, the lumen may be about 0.017″ in diameter. Themicrocatheter 130 may have a stainless steel braid structure. Themicrocatheter 130 may also have a hydrophilic coating. In certainembodiments, the microcatheter 130 may have an ultra-low profile.Preferably, the microcatheter 130 may be highly flexible and/ortrackable (via, e.g., the use of a radiopaque marker band). While themicrocatheter 130 may be highly flexible, in certain embodiments, themicrocatheter is more rigid than the guidewire. Thus, the microcatheter130 may provide additional support for the guidewire. The tip of themicrocatheter 130 may be tapered. In one embodiment, the microcatheter130 may have a soft, tapered tip. A microcatheter with a soft, taperedtip may be used for a coronary vasculature. In another embodiment, themicrocatheter 130 may have a stiffer, tapered tip. A microcatheter witha stiffer, tapered tip may be used for use in a peripheral vasculature(e.g., below the knee). In one embodiment, the microcatheter 130 mayhave 2.7F body and 1.7F tip. The length of the microcatheter 130 may beabout 150 cm, alternatively about 160 cm.

FIG. 5 shows an unwrapped view of an embodiment of a scaffold in anexpanded state in accordance with principles of the invention.Specifically, FIG. 5 shows a scaffold structure, which includes cellsand connectors. The connectors project inward. While FIG. 5 shows a dualloop embodiment, which contains two loops (e.g., a pair of loops), thenumber of loops may vary.

FIG. 5 shows one embodiment of a configuration of a self-expandablescaffold structure 341, which is utilized in a similar manner toself-expandable scaffold structure 145. (See also, FIGS. 8A-9D, forexample, and related description.) The expandable scaffold structure hasa central longitudinal axis and may be non-occluding. Theself-expandable scaffold structure 341(when in its wrappedconfiguration) is substantially cylindrical, but is shown flat and has aproximal end 365 and a distal end 367. The connectors 360, including, asshown, a pair of connectors may be in the form of a loop. Connectors 360are located in a pair with one at the proximal end 365 and the other inthe distally adjacent cell. The connectors 360 include a loop 342 and aloop support 344. The loops 342 may be located at strut intersections347. Loop supports 344 may couple the loops 342 to strut intersections347. The loop supports 344 may be tapered to reduce stress on theapparatus. The loop supports 344 may also be flexible. The scaffoldfurther includes struts 346, linking strut intersections 347, andconnectors 348. The struts 346 may be connected to connectors 348 atlinking strut intersections 347 or at strut intersections 345 if loopsare present. A connection between two struts 346 and two connectors 348via either two strut intersections or peaks and valleys 347, 345 or onestrut intersection 345 and one strut intersection 345 creates a closedcell 352 or a closed cell 350. A closed cell 350 includes a loop, whilea closed cell 352 does not contain a loop. The closed cells 350 and 352create the scaffold. The number of cells may vary. In one embodiment,the scaffold contains two closed cells 350 and the remaining closedcells are closed cells 352.

When in a cylindrical shape attached on an inner shaft, the loops 342may project inwardly from the cylindrical plane of the scaffold suchthat the inner shaft is positioned approximately in the center ofself-expandable scaffold structure 341. In one embodiment, the loops 342project inwardly from the cylindrical plane of the scaffold and theinner shaft passes through the loops such that the inner shaft maypositioned in the center of self-expandable scaffold structure 341. Theloops 342 center the inner shaft along a longitudinal axis of thedevice. The inner shaft is also positioned in the center of the chronictotal occlusion when in use. The loops may be circular, oval oblong orany additional shape, including, but not limited to closed shapes, toposition the inner shaft in the center of the self-expandable scaffoldstructure. Alternative numbers and configurations are possible.

The self-expandable scaffold structure 341 shown in FIG. 5 may be madeof nitinol or another shape-memory material. The loop connectors 348 mayalso be made of nitinol or another shape-memory material.

With reference to the embodiment of the self-expandable scaffoldstructures shown in FIG. 5, when the outer shaft is withdrawn fromaround the self-expandable scaffold structure, the self-expandablescaffold structure may expand to an expanded state. The outer shaft maybe partially or completely withdrawn from the expandable supportstructure. The inner shaft passes through loops 342 so during theexpansion of self-expandable scaffold structure, as the scaffoldingexpands, the loop supports connect the scaffold with the loops (loops342) that are disposed around the inner shaft causing the connectors 360to project/move/extend inward from the cylindrical plane of theself-expandable scaffold structure to hold the inner shaft in anapproximately centered position within self-expandable scaffoldstructure. As such, the inner shaft may be disposed and/or remainapproximately centered in the scaffold during expansion and compressionof self-expandable scaffold structure. Upon completion of a procedure,the self-expandable scaffold structure may be compressed and withdrawnfrom the vasculature. The outer shaft may be slid distally over theself-expandable scaffold structure. Preferably, no parts of the catheterapparatus extend outside of the cylindrical plane of the compressedself-expandable scaffold structure in the compressed state to facilitatewithdrawal of the catheter apparatus.

FIG. 6 shows another embodiment of a self-expandable scaffold structure349, which is used in a similar manner as self-expandable scaffoldstructure 145. Structure 349 is shown with a proximal end 390 and adistal end 392. The self-expandable scaffold structure 349 issubstantially cylindrical. The scaffold is comprised of cells with aloop structure at the distal end of the structure. In particular, thescaffold includes struts 351 which may be connected to strut connectors353 at strut intersections 355. The struts 351 when connected to strutconnectors 353 form closed cells 361 and 363. The cells, in oneembodiment, may be in approximately a honeycomb structure. The closedcells 361 and 363 create the scaffold. The number of cells in thescaffold may vary. The dimension of strut connector 353 may vary. In oneembodiment, the dimension of the strut connectors varies depending onwhether the self-expandable scaffold structure is expanded or collapsed.At the distal end 392 of the self-expandable scaffold structure 349, anattachment section 398 includes distal connectors 357 that may beconnected to struts 351 at strut intersection 355. The distal connectors357 may be connected to distal loop 359 via intersections 394. Thedistal connectors 357 may have a branched distal end 399. The distalconnectors 357, distal loop 359, and intersections 394 may form astructure that when crimped down on the inner shaft may create asphinctering effect. This sphinctering effect may hold theself-expandable scaffold in place at the attachment point (such as,e.g., a sleeve) on inner shaft while still allowing for sliding movementalong the inner shaft. This can be accomplished also by inverting thesection 398 as well. (See FIG. 11B for example.) In one embodiment, thescaffold structure may include such a configuration and/or loop networkalso at the proximal end.

The distal connectors 357 may have two branches at the distal end. Thus,each distal connector may be connected to distal loop 359 at twointersections 394. Preferably, the distal end is configured so thatdistal connectors 357 point inward towards the inner shaft. Thus, thedistal loops also face inward thereby creating a sphinctering effect.This sphinctering effect, which aids in the positioning of theself-expandable scaffold structure relative to the inner shaft.Alternative numbers and configurations are possible. Due to theintrinsic properties of the scaffold such as, e.g., the sphinctering,the inner shaft remains positioned approximately in the center ofself-expandable scaffold structure. Furthermore, inner shaft alsoremains approximately centered in the chronic total occlusion.

With reference to the embodiment of the self-expandable scaffoldstructure shown in FIG. 6, when the outer shaft is withdrawn around theself-expandable scaffold structure, the self-expandable scaffoldstructure may expand to an expanded state. The outer shaft may bepartially or completely withdrawn from the expandable support structure.During the expansion of self-expandable scaffold structure, the sectionand/or loop network at the distal end 392 of the scaffold may create asphinctering effect. The inner shaft may remain approximately centeredduring expansion and compression of self-expandable scaffold structure.Also, during the expansion the angle of the connectors 353 relative tothe cells 361 and/or 363 may change. Similarly, during the expansion theangle of the distal connectors 357 relative to the distal loop 359 mayalso change. Upon completion of a procedure, the self-expandablescaffold structure may be compressed and withdrawn from the vasculature.The outer shaft may be slid distally over the self-expandable scaffoldstructure. Preferably, no parts of the catheter apparatus extend outsideof the cylindrical plane of the compressed self-expandable scaffoldstructure in the compressed state to facilitate withdrawal of thecatheter apparatus.

The self-expandable scaffold structure 349 shown in FIG. 6 may be madeof nitinol or another shape-memory material. The strut connectors 353and distal connectors 357 may also be made of nitinol or anothershape-memory material.

FIG. 7 shows another embodiment of a self-expandable scaffold structureof the invention. FIG. 7 is a close-up view of a self-expandablescaffold structure 405 positioned on inner shaft 400. The scaffoldstructure 405 and inner shaft 400 are part of a catheter apparatus asdescribed above (e.g., a catheter apparatus including an outer shaft, aninner shaft, a self-expandable scaffold, and a microcatheter). Thescaffold structure includes proximal end 410 and distal end 415. Thescaffold structure 405 may be attached to the inner shaft 400 via theproximal end 410, preferably, fixedly attached. The scaffold structure405 may be held in place at the distal end 415 alone or with a sleeve(not shown) such that the scaffold structure is slideably along theshaft. The self-expandable scaffold structure 405 is cellular shape(such as, e.g., a honeycomb). The proximal end 410 and the distal end415 of the scaffold remain crimped on the shaft while the main body ofthe scaffold expands.

FIG. 8A shows a perspective view self-expanding scaffold in its expandedstate positioned on an inner shaft of a catheter apparatus in accordancewith one embodiment of the invention. With reference to FIG. 8A,scaffold 450 is shown in an expanded and generally cylindrical form.Scaffold 450 includes a wall defining an interior space. Expandedself-expandable scaffold 450 is shown with inner shaft 455 passingthrough the center of the approximately cylindrical scaffold 450.Connectors 460 include loops 460A and loop connectors 460B. Loopconnectors 460B connect the loops 460A to the scaffold 450. The innershaft 455 passes through the loops 460A. The connectors 460 projectinwardly from the cylindrical plane of the scaffold 450. Specifically,the loop connectors 460B are flexible so that the angle at which theloop connector 460B projects inward changes (e.g., increases, forexample, when the scaffold is expanded from the unexpanded/crimpedstate). The expanded self-expandable scaffold 450 is shown with oneconnector 460 towards the distal end of the scaffold and one connector460 towards the proximal end of the scaffold. The connectors 460 may bedisposed on or attached to the distal and/or proximal ends of thescaffold 450. The expandable scaffold may have two or more connectors,preferably in the form of loops. In one embodiment, the expandablescaffold has two connectors, preferably in the form of loops. Eachconnector 460 has loops 460A through which the inner shaft 450 may passand a connector 460B, which is attached to the scaffold 450. Theconnectors 460 are configured such that the inward facing loops positionthe inner shaft 455 along a longitudinal axis (shown in FIG. 8A) passingapproximately through the center of the scaffold 450. The loops ofconnectors 460, when the scaffold 450 is in its expanded state, alignalong a longitudinal axis L running approximately through the center ofthe scaffold. The scaffold 450, inner shaft 455 and loops 460A all sharea common longitudinal axis and/or have a concentric axis. As the innershaft 455 passes through these loops, it positioned along this axis andis thereby approximately centered in the scaffold. The length of theconnectors 460 may also define the maximal expansion obtainable by thescaffold. Specifically, for a connector having a circular shape or loopthe maximal expansion obtainable by a scaffold with at least twoconnectors is the length of two connectors and the diameter of the loop.The angle at which connectors project inwardly may vary. In oneembodiment, each connector may project inwardly at the same angle. Asshown, the loops 460A define a plane this is substantially perpendicularto the longitudinal axis L.

FIG. 8B is a perspective view of a loop of a scaffold in accordance withprinciples of the invention. Specifically, FIG. 8B shows one connector460 (which may be used in a scaffold as described above with referenceto FIG. 8A) having loop 460A and loop connector 460B. The loop 460A isconfigured for passing over a catheter. The size and configuration ofthe loop 460A may vary depending on the use. In one embodiment, the loop460A may be approximately circular. Loop connector 460B connects theloop 460A to a scaffold. The loop connectors 460B may be may be taperedto reduce stress on the scaffold. The loop connectors 460B areconfigured to move, restore, flex and/or bend as the scaffold expandsbecause one end is attached to the scaffold and the other end isattached to the shaft by the loop. This may be achieved for example byconstructing the loop connectors 460B from a memory shape alloy such asnitinol. Specifically, the loop connectors 460B may be configured sothat they project inwardly from the inner surface of the scaffold whenthe scaffold is fully expanded.

FIG. 9A is a view of the distal end of a catheter apparatus 465according to one embodiment of the invention. FIG. 9A shows the distalend of a catheter apparatus with outer shaft (sheath) 467 in a partiallyretracted position. Catheter apparatus 465 can have any of the featuresof a catheter apparatus disclosed herein. In particular, catheterapparatus 465 includes expansible scaffold 471 having a proximal anddistal end. The scaffold 471 is disposed on the distal end of the innershaft 469. The proximal end of the scaffold 471 is secured to 469. Whilethe distal end is not attached to 469 as shown in the expandedconfiguration in FIG. 9A. The expansible scaffold 471 may include acellular configuration of cells 470. Each cell 470 is approximatelyhexagonal and has expansible S-shaped (zig-zag) connectors 472 on twoopposing sides of the hexagon. In one embodiment, these S-shaped(zig-zag) connectors are approximately parallel to an axis passingthrough the center of the scaffold from the distal to the proximal end.The scaffold also includes connectors 474 including the type describedherein such as inward projecting loops. The loops are configured forallowing the inner shaft 469 to pass through them. The number andconfiguration of the loops and cells, including the connectors, mayvary. The connectors 474 center the shaft 469 in the scaffold 471. As inother embodiments of the invention, the outer shaft 467 is movablerelative to the inner shaft. Optional outer shaft tip 477 is configuredfor passing over the expansible scaffold 471. The catheter apparatusfurther includes microcatheter 473 which passes through a lumen in innershaft 469. Microcatheter 473 has a lumen through which guidewire 475 maypass. Similar to the other embodiments of the invention, inner shaft469, microcatheter 473 and guidewire 475 may telescope independently ofeach other, in both directions. As shown, for reliable centering of themicrocatheter the scaffold 471 and inner shaft 469 share a commonlongitudinal axis L and are concentric.

FIG. 9B illustrates an embodiment of the steps during a method usingcatheter apparatus 465 shown in FIG. 9A the catheter apparatus 465approaches the CTO tracking along guide wire 475 positioned proximatethe CTO but unable to cross. In FIG. 9B, catheter apparatus 465 is shownin six steps inserted into vasculature 479 having occlusion 481. FIG. 9Bshows a cut away of the vasculature 479 and chronic total occlusion 481with catheter apparatus 465. Steps 1 and 2 of FIG. 9B show the outershaft or sheath 467 covering the expansible scaffold 471 and hold it inan unexpanded position. The inner shaft 469 is threaded through the loop460A. The first step of the operation of the catheter apparatus 465 isinsertion of the catheter apparatus 465 into vasculature 479 close toocclusion 481. As shown in Step 1, the catheter apparatus 465 isadvanced with the scaffold 471 in its refracted or compressed position.In the retracted position, scaffold 471 is covered by outer shaft 467and outer shaft tip 477. Guidewire 475 has been advanced into contactwith occlusion 481 as shown in step 1 for the system to track over. Thecatheter apparatus 465 is advanced over guidewire 475 towards the CTO481 as shown in step 1 with the catheter apparatus approaching the CTO.Once the catheter apparatus has been engaged or contact with the CTO orin close proximity to the CTO, as shown in step 2, outer shaft tip 477is in close proximity to the occlusion 481, in particular, contacts theleading edge of the CTO. Expansible scaffold 471 is still in itscompressed or non-expanded position. The outer shaft 467 is thenretracted or withdrawn such that the expansible scaffold 471 assumes itsexpanded state (as shown in step 3). Expansible scaffold 471 has loopsthrough which the inner shaft 469 is positioned and microcatheter 473 ispositioned in the inner shaft. All are centered in the scaffold whenexpanded (as shown in step 3). Thus, microcatheter 473 is substantiallycentered in vasculature 479. Step 1 shows catheter apparatus 465advanced into vasculature 479 with guidewire 475 extended but withoutsufficient support to cross the CTO/lesion. Step 2 shows the catheterapparatus 465 advanced by tracking over the guidewire 475 so that outershaft tip is pushed against the (leading) edge of the CTO. Steps 4 and 5of FIG. 9B show further advancement of the guidewire 475 into contactwith and through the occlusion 481. Alternatively, the microcatheter 473may also be advanced into contact and through the occlusion 481. Step 6shows catheter apparatus 465 with microcatheter 473 and guidewire 475advanced through the occlusion 481. The microcatheter 473 adds supportto the guidewire 475 as it passes through the CTO. The guidewire and themicrocatheter can be advanced alternatively back and forth.

FIG. 9C is a close-up view of the distal end of catheter apparatus 465shown in FIG. 9A with outer shaft (sheath) 467 in a partially retractedposition. As discussed above with reference to FIG. 9A, catheterapparatus 465 includes expansible scaffold 471 having a proximal enddisposed on the outer shaft 467, while the inner shaft 469 passesthrough the scaffold 471. The expansible scaffold 471 may be configuredso that it has a central longitudinal axis L along which the inner shaft455 passes. The expansible scaffold 471 includes cells 470. Each cell isapproximately hexagonal and has expansible S-shaped (zig-zag) connectors472 on two opposing sides of the hexagon. The scaffold also includesinward projecting loops 460A, which are configured for passing the innershaft 455 therethrough. The loops 460A may project inward so that theloops are positioned along the central longitudinal axis L of theexpansible scaffold 471. The optional outer shaft tip 477, which may betapered, is also shown. In certain embodiments, the outer shaft tip 477may be used to maintain the position of the expansible scaffold 471. Thetaper of the outer shaft tip 477 may assist in allowing the outer shaft467 to pass over the scaffold 471, and may also be beneficial innavigating the catheter into inner branches of the vasculature.

FIG. 9D is a distal end view of the distal end catheter apparatus 465shown in FIG. 9A and 9B. Specifically, as shown in FIG. 9B, the innershaft 469 is shown positioned along the central longitudinal axis ofexpansible scaffold 471 via inward projection loop 474. Thisconfiguration allows the device to the centered in a vasculature whilein operation and, more particularly, to center the microcatheter. Thus,the guidewire as shown in FIG. 9B may pass through the center of theCTO. Microcatheter 473 is shown passing through the inner shaft 469.Guidewire 475 (not shown) may pass through microcatheter 473.

FIGS. 10A to 10C illustrate alternate embodiments of scaffolds useful inthe catheters apparatus of the invention. For illustration purposes onlythe scaffold are shown on the inner shaft. When used in a catheterapparatus of the invention, the apparatus may include the inner shaft,outer shaft, scaffold, and other features as described herein. In thisembodiment, the scaffold is configured without outwardly extendingextensions with free ends. As shown, these extensions may be describedas forming the shape of a flower with the inner shaft passing throughthe center and the petals of the flower (i.e., the arms of the scaffold)radiating out from inner shaft when the scaffold is expanded. Morespecifically, this “flower” scaffold includes a center band and armsthat are attached to the center band at one end and the other end isflexible. The center band is disposed on the inner shaft. The armsexpand radially out from the center band to a predetermined diameter.This predetermined diameter may be based on flexibility of the materialused to manufacture the arms. The arms of this embodiment may aid withthe centering of the inner shaft, microcatheter, and/or guidewire.

FIG. 10A shows inner shaft 485A which has one or more expansiblescaffolds 487A disposed towards the distal end of the shaft. The innershaft 485A has a lumen for passing a microcatheter. The scaffolds 487Aare shown in their expanded position. One of the one or more scaffolds487A may be attached to the distal end of the inner shaft 485A. Whileone or two scaffolds 487A may be used in certain embodiments of theinvention, the number and configuration of the scaffold varies dependingon the use. Thus, in certain embodiments, one or more, two or more orthree or more of scaffolds 487A may be used. Each of the one or morescaffolds 487A includes a center band 489A and arms 491A. The arms 491Amay be thin strips of material which may be rounded towards their distalend. The number of arms in each of the scaffolds may vary depending onuse. For example, the scaffold may contain three, four, six or eightarms or other combinations. More arms provide more coverage andpotentially better centering. The scaffold size and flexibility maydecrease as the number of arms increase. Arms 491A may be disposed on,attached to or integral with center band 489A. Center band 489A isdisposed on inner shaft 485A.

FIG. 10B is a perspective view of inner shaft 485B havingself-expansible scaffolds 487B. Like in FIG. 10A, the scaffolds areshown in their expanded position. Each of the arms 491B of the scaffold487B may have openings 493B towards their distal end. The openings 493Bmay be approximately circular, rectangular or oval. The configuration ofopenings 493B may vary depending on the use. When in a vasculature, thearms 491B may contact the surface of the vasculature when scaffold 487Bis expanded. When expanded, the arms may curve such that they contactthe vasculature towards their distal end. The arms 491B may be curved tomaximize the contact area between the distal end of the arms and thesurface of the vasculature. For example, the distal end of the arms 491Bmay curve such that the distal tip of the arms 491B is approximatelyparallel to the inner shaft 485B when the scaffold is fully expanded.The openings in the arms help to increase flexibility while coveringmore surface area. The surface area is important since it helps tospread the force of the arms on the vessel wall. Each center band 489Bmay have openings 495B around its circumference. The openings 495B maybe approximately rectangular although the configuration and number ofthe openings 495B may vary depending on the use. The openings in thecenter band of the scaffold may provide for additional reinforcement tothe scaffold and inner shaft bond. The center band may be attached tothe inner shaft via a biocompatible adhesive. The adhesive is meant tofill the gap between the center band and inner shaft. The adhesive isalso meant to partially fill the openings on the center band, creatingan additional mechanical lock for this bond.

FIG. 10C is an unwrapped view of scaffold 487C, which is anotherembodiment a “flower” scaffold. As shown in FIG. 10C, the openings 495Cin center band 489C may be oval. The shape and number of the openingsmay vary depending on their use. With reference to FIG. 10C, each of thearms 491C of the scaffold 487C has distal opening 493C at their end.Furthermore, each of the arms may have further openings 497C. Theopenings in the arms may help to increase flexibility of the arms whilecovering more surface area. This surface area helps to spread the forceof the arms on the vessel wall. As shown in FIG. 10C, the arms 491C maybe integrally formed with center band 489C. Thus, the scaffold may bemade from a single sheet of self-expansible material such as, e.g., afoil. In alternate embodiments, the scaffold may be assembled bymounting the arms 491C onto center band 489C.

Nitinol and/or stainless steel may be incorporated into scaffolds 487A,487B, and 487C. Nitinol is an illustrative example of a shape memoryalloy. Other shape memory alloys or other similar substances may beused.

A scaffold configured as shown in FIG. 10A-C has certain benefits.First, it may be more flexible since it not one continuous piece, buttwo or more pieces. Second, the arms may be added or removed and spacedoptimally to help provide optimal centering. Furthermore, due theconfiguration of the scaffold, the inner shaft remains is positionedapproximately in the center of self-expandable scaffold structure.Furthermore, inner shaft also remains approximately centered vessel inthe chronic total occlusion. In addition, where one or two scaffolds areused, the scaffold of the catheter apparatus can be compact providingfor a low profile. This can make delivery and use easier.

Like the other scaffolds of the invention, the “flower” scaffoldprovides self-expanding, anchoring support and may be non-occlusive,allowing blood flow to collateral and branch vessels. Optimally, thescaffold has a broad working range (i.e., one size fits all). Thescaffold may also be tailored for the specific intended uses. Thestructure may be used alone, and/or in combination with other structuresand/or features, to position the catheter apparatus in the artery and toposition the one or more microcatheters substantially centered in themiddle of the scaffold/artery. The scaffold may be atraumatic to thevessel wall thereby requiring minimal hoop strength to maintainposition. The scaffold is configured to re-sheath to facilitatewithdrawal and can be employed multiple times.

FIGS. 11A to 11C are views of the distal end of catheter systems inaccordance with embodiments of the invention with different exemplarysuitable self-expandable scaffold configurations. FIG. 11A is a view ofa distal end of a catheter apparatus having an open-ended scaffold inaccordance with one embodiment of the invention. This scaffoldconfiguration is similar to the configuration shown in FIG. 9A and ischaracterized by a scaffold which has inward facing loops through whichthe inner shaft passes. The distal end of the scaffold is attached tothe inner shaft. FIG. 11B is a view of a distal end of a catheterapparatus having a scaffold as described above in FIGS. 2A, 2B, and 7.This “football” scaffold is characterized by being approximatelycylindrical in shape and with the ends curving towards the inner shaft.The distal end of the scaffold is disposed towards the distal end of theinner shaft without being attached. The proximal end of the scaffold isattached to the distal end of the inner shaft. FIG. 11C is a view of adistal end of a catheter apparatus having a scaffold similar to thatdescribed in FIGS. 10A to 10C in accordance with principles of theinvention.

In particular, FIG. 11A shows catheter apparatus 501 having inner shaft503, microcatheter 505 and expansible scaffold 509. The catheterapparatus may further have a retractable sheath, which may slide overthe inner shaft 503 and expansible scaffold 509. The inner shaft 503 hasone or more lumens. The microcatheter 505 passes through one of the oneor more lumens in the inner shaft. The microcatheter 505 has a lumenconfigured for passing guidewire 507. The microcatheter 505 may havemarker band 508 towards its distal end. The expansible scaffold 509 hasa cellular configuration. The scaffold further includes one or moreinward facing connectors 515 through which the inner shaft 503 passes.The inward facing loops project inwardly from the cylindrical plane ofthe scaffold. In one embodiment, the scaffold has two inward facingloops 515. In that embodiment, one of the inward facing loops 515 may bepositioned towards the proximal end of the scaffold, while the other maybe positioned towards the distal end. The scaffold is configured so thatupon expansion of the scaffold, the inner shaft 503 and therefore alsomicrocatheter 505 and guidewire 507 are centered in the scaffold viainward facing loops. Specifically, this configuration is achievablebecause the inward facing loops (when the scaffold is expanded) align tocreate and/or maintain a common a longitudinal axis through the centerof the scaffold, inner shaft, and microcatheter. The inner shaft 503passes through the inward facing loops and therefore along thelongitudinal axis of the device when the scaffold is in its expandedstate. Thereby the inner shaft is centered in the scaffold. Since thescaffold when in use is centered in a chronic occlusion, after expansionand in-situ, the inner shaft 503 and therefore also microcatheter 505and guidewire 507 are also centered in the chronic occlusion. They sharea common longitudinal axis. The inward facing connectors 515 areconnected to the scaffold via the loop support and loop configurationdescribed herein. In one embodiment, the connector is approximatelylinear when the scaffold is in its expanded state.

FIG. 11B shows catheter apparatus 517 having inner shaft 519 withscaffold 525 disposed towards the distal end. Microcatheter 521 passesthrough a lumen in inner shaft 519. Microcatheter 521 is also configuredfor passing guidewire 523. The scaffold 525 has a distal end and aproximal end. The proximal end of scaffold 525 is disposed on orattached to towards the distal end of inner shaft 519. The distal end ofscaffold 525 is disposed on or attached to the distal end of inner shaft519, preferably slidably disposed or attached. The distal end of thescaffold 525 may be slidably disposed or attached to the inner shaft 519by, for example, an inverted portion 520 of the scaffold 525. Theexpansible scaffold 525 includes a cellular configuration. Themicrocatheter may have a marker band 533 towards the distal end.Optionally, catheter apparatus 517 also has a retractable sheath 531which may slide over the inner shaft 519 and expansible scaffold 525.The scaffold is configured so that upon expansion that upon expansion ofthe scaffold, the inner shaft 519 and therefore also microcatheter 521and guidewire 523 are centered in the scaffold. Since scaffold when inuse is centered in a chronic occlusion, inner shaft 519 and thereforealso microcatheter 521 and guidewire 523 are also centered in thechronic occlusion.

FIG. 11C shows catheter apparatus 537 having inner shaft 539, one ormore expansible scaffolds 547 and microcatheter 541. The inner shaft 539has one or more lumens. The microcatheter 541 passes through a lumen inthe inner shaft 539. The microcatheter 541 is configured for passing aguidewire 543. Optionally, the microcatheter 541 includes a marker band545. The one or more expansible scaffolds are of the type havingprojections, fingers, tabs or members as shown above in FIG. 10A to 10C.In one embodiment, they may be a “flower scaffold.” Each of the one ormore expansible scaffolds 547 have a center band 549 which is disposedon or attached to the inner shaft 539. Attached to each center band 549are arms 551, which radiate out when the scaffold expands. The arms 551may be wire loop with one or more openings. In another embodiment, thecenter band 549 and arms 551 are made from a sheet of self-expandingmaterial such as nitinol. When the one or more scaffolds expand in anocclusion, the inner shaft 539 (and, therefore, also the microcatheter541 and guidewire 543) are centered in the occlusion.

FIG. 12A shows a proximal end of a catheter system in accordance withanother embodiment of the invention. The inner shaft 469 may be disposedwithin the outer shaft 467 through an opening in the outer shaft hub567. Microcatheter 473 can be disposed within the inner shaft 469through the inner shaft hub 569. The microcatheter hub 571 may includean opening through which a guidewire (not shown) may inserted. Any ofthe outer shaft 467, inner shaft 469, and microcatheter 473 may bemovable independently of the others. For example, during use of thecatheter, an operator of the catheter may grip one or more of hubs 567,569, and 571 in order to move one or more of the hubs relative toanother. This results in a relative sliding of the outer shaft 467,inner shaft 469, or microcatheter 473 with respect to the others. Theouter shaft 467 also may include a port 568 near or integral with theouter shaft hub 567. A lumen of the port 568 may be in fluidcommunication with a longitudinal lumen of the outer catheter.

FIG. 12B shows a distal end of the catheter system according to anembodiment. Specifically, FIG. 12B shows the relative positions of theouter shaft 467 and inner shaft 469 when the proximal end of thecatheter apparatus is in the position shown in FIG. 12A. For example,when the outer shaft hub 567 and the inner shaft hub 569 are spacedapart in the manner shown in FIG. 12A, the distal end of the inner shaft469 is disposed within the distal end of the outer shaft 467. In thisway, the scaffold 473 (not shown in FIG. 12B) may be contained in anon-expanded state within the outer shaft 467.

FIG. 12C shows the proximal end of the catheter after the outer shafthub 567 and the inner shaft hub 569 are moved relative to one another.For example, the outer shaft hub 567 may be moved in the proximaldirection (i.e., away from the distal end of the catheter), as indicatedby arrow A in FIG. 12C. However, it is also possible to move the innercatheter hub 569 in the distal direction (i.e., the opposite of arrow A)while holding the outer shaft hub 567 in place. Though not shown, themicrocatheter hub 571 may be moved relative to the outer and inner shafthubs 567, 569 in a similar fashion.

FIG. 12D shows the distal end of the catheter when the proximal end isarranged as shown in FIG. 12C. As shown in FIG. 12D, by shortening thedistance between outer shaft hub 567 and inner shaft hub 569 (see FIG.12C), the distal end of inner shaft 469 and the scaffold 473 haveemerged from the distal end of the outer shaft 467, and the scaffold 473has therefore expanded to an expanded state.

With reference to FIGS. 13A-13B, a method is described using thecatheter apparatus shown, for example, in FIG. 12A. Although illustratedwith an embodiment of the catheter apparatus as shown, the othercatheter embodiments and various combinations thereof described andincorporated herein may also be used in accordance with the methodsdescribed herein.

FIGS. 13A-13B illustrate an embodiment of the steps during a methodusing catheter apparatus 465 shown in FIG. 13A. The catheter apparatus465 approaches the CTO tracking along guide wire 475 positioned inproximity of the CTO but unable to cross. In FIG. 13A, catheterapparatus 465 is shown in six steps inserted into vasculature 479 havingocclusion 481. FIG. 13A shows a cut away of the vasculature 479 andchronic total occlusion 481 with catheter apparatus 465. Steps 1 and 2of FIG. 13A show the outer shaft or sheath 467 covering the expansiblescaffold 471 and hold it in an unexpanded position. The inner shaft 469is threaded through the loop 460A. The first step of the operation ofthe catheter apparatus 465 may be insertion of the catheter apparatus465 into vasculature 479 close to occlusion 481. As shown in Step 1, thecatheter apparatus 465 can be advanced with the scaffold 471 in itsretracted or compressed position. In the retracted position, scaffold471 can be covered by outer shaft 467 and outer shaft tip 477. Guidewire475 has been advanced into contact with occlusion 481 as shown in step 1for the system to track over. The catheter apparatus 465 may be advancedover guidewire 475 towards the CTO 481 as shown in step 1 with thecatheter apparatus approaching the CTO. Once the catheter apparatus hasbeen engaged or contact with the CTO or in close proximity to the CTO,as shown in step 2, outer shaft tip 477 may be in close proximity to theocclusion 481, in particular, contacts the leading edge of the CTO.Expansible scaffold 471 is still in its compressed or non-expandedposition. The outer shaft 467 can then be retracted or withdrawn by, forexample, decreasing a distance between the outer shaft hub 567 and innershaft hub 569, as shown in FIG. 12C. The expansible scaffold 471 assumesits expanded state (as shown in step 3). Expansible scaffold 471 hasloops through which the inner shaft 469 may be positioned andmicrocatheter 473 is positioned in the inner shaft. All are centered inthe scaffold when expanded (as shown in step 3). Thus, microcatheter 473can be substantially centered in vasculature 479. Step 1 shows catheterapparatus 465 advanced into vasculature 479 with guidewire 475 extendedbut without sufficient support to cross the CTO/lesion. Step 2 shows thecatheter apparatus 465 advanced by tracking over the guidewire 475 sothat outer shaft tip may be pushed against the (leading) edge of theCTO. Steps 4 and 5 of FIG. 13A show further advancement of the guidewire475 into contact with and through the occlusion 481. Alternatively, themicrocatheter 473 may also be advanced into contact and through theocclusion 481. Step 6 shows catheter apparatus 465 with microcatheter473 and guidewire 475 advanced through the occlusion 481. Themicrocatheter 473 may add support to the guidewire 475 as it passesthrough the CTO. The guidewire and the microcatheter can be advancedalternatively back and forth to penetrate through the CTO. AlthoughSteps 7-10B in FIG. 13B show the guidewire 475 penetrating through aportion of the occlusion (CTO) 481, it is understood that the guidewiremay alternatively be advanced through the entirety of the occlusion 481.

In FIG. 13B, steps are shown of removal of the inner shaft 469 andscaffold 471. The microcatheter 473 may be withdrawn as it isindependent from the inner and outer shaft. The result of withdrawingthe microcatheter is shown in Step 8 of FIG. 13B, where only theguidewire is disposed through the CTO. Next, the scaffold 471 may bereturned to its non-expanded state by advancing the outer shaft 467 inthe distal direction until the scaffold is contained with the outershaft 467, or at least until the scaffold 471 is not expanded.Alternatively, as shown in step 8, the inner catheter 469 may be movedproximally so that the scaffold 471 is received within the outer shaft467. It is understood from the above discussion that the relativemovement of the inner and outer shafts 467 and 469 may be achieved bythe relative movement of the proximal ends of these shafts. The hubs567, 569 of FIG. 12C, for example, may be moved relative to each otherto achieve Step 8, for example. As shown in Step 9 of FIG. 13B, theinner catheter 469 and scaffold 471 may be completely removed from thevasculature. If removed completely from the outer shaft 467 via aproximal opening of the outer shaft 467, the outer shaft 467 may remainpositioned near a target location within the vasculature. Accordingly,an angioplasty balloon, stent, catheter, scope, imaging or treatmentdevice/material, or additional interventional instrument or medicaldevice (shown in various embodiments as 476 in Steps 10A and 10B of FIG.13B) may then be placed in the vasculature, as shown in Step 10, usingthe outer shaft 467 as a guide and as protection for the patient'stissue. The guidewire 475 may also assist in guiding the additionalinstrument 476, as the guidewire 475 may be left penetrating theocclusion 481 even after removal of the inner catheter 469, as shown inSteps 8-10 of FIG. 13B.

FIG. 14 shows another embodiment of the proximal end of the catheter.

FIGS. 15A-15E shows an example of a catheter according to an embodimentof the invention being used in accordance with an embodiment of themethod shown in FIGS. 13A-13B. This example is performed in a model 572with channels 575 that represent vasculature of a patient. As shown inFIG. 15A, the outer shaft 467 is inserted into the vasculature and theinner shaft has not yet been deployed. A guidewire 475 may be used toinsert the outer shaft 467 to the position shown. In FIG. 15B, the innershaft 469 and scaffold 473 have been deployed from the outer shaft 467.Additionally, the guidewire 475 extends out from the distal end of theinner shaft 469. In FIG. 15C, a microcatheter 473 and the guidewire 475have both been further into the vasculature in order, for example, toadvance through an CTO (not shown).

After using the microcatheter 473 in FIG. 15C for its intended purpose,the microcatheter 473 and inner shaft may optionally be withdrawn fromthe vasculature through the outer shaft 467. FIG. 15D shows an examplewhere the inner shaft 469 and scaffold 473 have been retracted throughthe outer shaft 467. In some embodiments, the microcatheter 473 andinner shaft 469 are completely removed from the outer shaft 467 througha proximal opening in the outer shaft 467, as discussed above. Theguidewire 475 may remain inserted into the vasculature, or may bereinserted after removal of the microcatheter 473 and inner shaft 469.Subsequently, as shown in FIG. 15E, at least one additional instrument573 may be inserted into the vasculature through the outer shaft 467.The guidewire 475 may also be used for positioning the additionalinstrument 573. The additional instrument 573 may be, for example, apercutaneous transluminal coronary angioplasty balloon or stent, or someother interventional or surgical device. Because the outer shaft 467remains in position even after removal of the inner shaft 469, theadditional instrument 573 may be more easily and safely guided to thetarget through the outer shaft 467. In this way, there is a reduced riskof trauma to the tissues of the patient when moving the additionalinstrument 573 through the vasculature, and it is easier to advance tothe target location without being diverted.

Although shown and described with respect to one inner shaft and that iscentered within the vasculature by the scaffold, embodiments of thepresent invention can be used with catheters that have multiple innershafts or microcatheters and no one inner shaft or microcatheter needsto be centered within the vasculature. Alternatively, in a multi-innershaft configuration, one inner shaft may be centered within thevasculature while one or more other inner shafts are offset from thecenter of the vasculature. The use of the scaffold CTO to position andcross the lesion, and beneficially position the outer shaft or sheathclose to the lesion can be accomplished with the various scaffoldembodiments described herein and in the applications incorporated byreference and to which priority is claimed.

The configuration of the devices of the invention may vary. In certainembodiments, the devices are configured for use in vessels that have adiameter from about 2.5 mm to about 4.0 mm. The devices may beconfigured for an OTW 0.014″ guidewire lumen. In certain embodiments,the microcatheter is 3 F microcatheter, which may be up to 150 cm inlength. The devices may be configured to be compatible with a 6FR guidecatheter and have a 5F sheath. Distinguished radiopaque markers may beused on various parts of the device such as the tip of the inner shaft,outer shaft, and/or microcatheter to aid with determining the positionof the device in the body. In certain embodiments, the device may have aworking length of about 130 cm. A hydrophilic coating may also be usedon part of the device. The outer shaft 467 may be formed of a materialthat maintains a substantially circular cross-section when the innercatheter and scaffold are removed, but the outer shaft may also be softand flexible enough to be navigable through the tortuous branches of theinner vasculature.

According to embodiments of the present invention, a catheter may beprovided that serves a dual purpose. For example, the catheter may beused for a first purpose of advancing a guidewire and inner- ormicrocatheter to a target area within the vasculature where, in someembodiments, a scaffold is expanded to aid in advancing the guidewireand/or microcatheter through a CTO. Additionally, as a second purpose,the catheter can act as a support catheter that remains in thevasculature such that a distal end of the support catheter remains closeto the target location during and/or after the scaffold andmicrocatheter, for example, are removed from the support catheter. Assuch, the catheter can serve as a support catheter for additionalmedical devices or therapeutic agents. These medical devices caninclude, for example, additional catheters, scopes, imaging or treatmentmaterials/devices, angioplasty balloons, rotoblades, and/or atherectomydevices. However, other medical devices may also be used in conjunctionwith the guide catheter in its dual purposes. In addition, therapeuticagents such as medicinal, imaging, or irrigation materials may be passedthrough the support catheter to the target area.

Navigating instruments through the vasculature can be difficult,especially when a target area of the procedure is located within abranch of the vasculature that is off a main trunk of the vasculature.For example, smaller branches are tortuous and extend at angles from themain truck, but instruments will tend to remain straight and thus it canbe difficult to steer the instrument into a branch. In addition, thetarget area may be in still more-distally located branches, which canmake reaching the target even more difficult due to the tortuosity ofthe anatomy. This difficulty is apparent even for devices with arelatively low profile, such as deflated angioplasty balloons, which,though low profile, will tend to proceed straight through a main trunkand resist being steered into side branches.

However, the dual purpose catheter provides a support catheter forreliably reaching the target area after the initial placement of thecatheter near the target area. In other words, the support catheter candirect additional medical devices through the tortuous anatomy to thetarget location, without requiring the difficult re-navigating of theanatomy each time a new device is inserted into the vasculature. Thus,in some embodiments, the dual purpose catheter may be a support catheterthat differs in construction from so-called guide catheters in that thesupport catheter is more flexible to enable navigation of the innervasculature.

Because the location of a lesion or occlusion, for example, may be in abranch of the vasculature that is one or more than one turn off of themain trunk, the difficulty in reaching the occlusion can vary.Therefore, in embodiments of the present invention, the target area maybe in the immediate vicinity of the occlusion, in a branch in which theocclusion is located, or in a branch from which the branch containingthe occlusion is disposed (even if the branch containing the occlusionis multiple turns off of the branch of the target area). Even if thespecific branch containing the occlusion cannot be reached by thecatheter, advancing the distal end of the catheter as close as possibleto the occlusion can provide significant benefits over positions thatare farther from that “close as possible” location. Thus, in someembodiments of the present invention, it is contemplated that the distalend of the catheter may not be advanced to the immediate vicinity of theocclusion for some patients. Even so, the dual use catheter may providethe same benefit of reaching a target area and for advancing additionalmedical devices to that target area.

While the invention has been described and illustrated herein byreferences to various specific materials, procedures and examples, it isunderstood that the invention is not restricted to the particularcombinations of material and procedures selected for that purpose.Numerous variations of such details can be implied as will beappreciated by those skilled in the art. It is intended that thespecification be considered as exemplary, only, with the true scope andspirit of the invention being indicated by the following claims.

Although the foregoing description is directed to the preferredembodiments of the invention, it is noted that other variations andmodifications will be apparent to those skilled in the art, and may bemade without departing from the spirit or scope of the invention.Moreover, features described in connection with one embodiment of theinvention may be used in conjunction with other embodiments, even if notexplicitly stated above.

What is claimed is:
 1. A method of using a catheter in a vessel of apatient for crossing a target area and providing support for a medicaldevice, comprising: inserting a catheter into a vessel such that adistal end of the catheter approaches a target area in the vessel, thecatheter comprising: a hollow shaft with a distal end and a proximalend, a non-occluding self-expandable scaffold disposed at the distal endof the catheter, wherein a portion of the distal end of the catheter isdisposed at least in part inside the scaffold, and a sheath with acentral lumen, a distal end having a distal opening, and a proximal endhaving a proximal opening, the sheath being slidable along the shaft,wherein the scaffold is configured to be coupled to the distal end ofthe catheter, and wherein the scaffold is in an un-expanded state whencovered by the sheath; withdrawing the sheath to expand theself-expandable scaffold; moving the sheath and the scaffold relative toeach other to position the sheath at least partially over the scaffoldsuch that the scaffold returns to the un-expanded state; and withdrawingthe hollow shaft and the scaffold through the proximal opening of thesheath, the sheath being adapted to remain in the vessel as a supportcatheter such that a medical device may be passed through the proximalopening of the sheath and advanced through the sheath to the target areanear the distal end of the sheath.
 2. The method claim 1, furthercomprising inserting a microcatheter through the catheter beforeadvancing the sheath over the scaffold to return the scaffold to theun-expanded state.
 3. The method of claim 1, further comprisinginserting a guidewire through the catheter until a distal end of theguidewire is disposed at the target area.
 4. The method of claim 3,wherein inserting the guidewire further comprises advancing theguidewire through the target area.
 5. The method of claim 3, wherein thedistal end of the guidewire remains disposed at the target area afterwithdrawing the hollow shaft and the scaffold.
 6. The method of claim 2,wherein the method further comprises advancing the microcatheter afterwithdrawing the sheath to expand the self-expandable scaffold, whereinthe microcatheter is adapted to contact a chronic total occlusion. 7.The method of claim 1, wherein at least a portion of the distal end ofthe catheter is disposed substantially along a central axis of thescaffold.
 8. The method of claim 1, further comprising inserting amedical device through the proximal opening of the sheath and advancingthe medical device through the sheath to the target area near the distalend of the sheath.
 9. The method of claim 8, wherein advancing themedical device through the sheath to the target area includes the methodbeing adapted to advance the medical device to an arterial branch thatis off of a main trunk.
 10. The method of claim 1, wherein the catheteris adapted to be inserted into an arterial branch that is off a maintrunk.
 11. The method of claim 1, wherein the target area is adapted tobe one or more of proximate to a chronic total occlusion, and anarterial branch of the coronary artery.
 12. The method of claim 1,wherein the non-occluding self-expandable scaffold is removable.